Happy Toilet Cleaner Review: How the In-Tank Tablet Holder Works, What It Cleans and What It Costs

Our verdict

Yes, if you already drop cleaning tablets into your toilet tank and want to stop them damaging the flapper and fill valve. Happy Toilet Cleaner is a plumber-designed, patented holder that routes refill water through the tablet and into the bowl, which is a genuinely sensible idea at about $15 to $25 a toilet. But it will not end scrubbing, it does not fit every toilet, Kohler warns that in-tank cleaners void its warranty, and you keep buying tablets. Happy Toilet Cleaner scores 5.6 out of 10, held back by overstated claims and thin independent evidence.

The short version

• A blue plastic holder that clips to the overflow tube inside a toilet tank.
• Refill water passes through a tablet in the chamber and drains into the bowl, so the tablet does not sit in the tank water.
• Invented by Arizona plumber Chris Stanfield; US patent 11,821,189 was granted in November 2023.
• $24.99 plus shipping for one on 3 October 2026; $49.98 for three and $74.97 for five with free shipping.
• The brand store listed the same single price, plus two for $44.80 and four for $63.96.
• Kohler toilets need the separate Deuce version, and Kohler says in-tank cleaners void its warranty.
• Best trait: it protects tank parts from loose tablets while still dosing the bowl.
• Biggest drawback: "never scrub again" oversells what any tablet can do.
• Our score: 5.6 out of 10.

Pros & cons

Happy Toilet Cleaner is a real product from a small Arizona company, built around a real plumbing problem. The cons are mostly about expectations, compatibility and the running cost of tablets.

How it works

Most toilets in North American homes are gravity-flush: a tank holds water, and pressing the handle lifts a flapper so the water drops into the bowl. A fill valve then refills the tank, and a small refill tube sends part of that water down the overflow tube to top up the bowl. Happy Toilet Cleaner sits in that refill path.

1. 01

   Clip it to the overflow tube

   Step 1: Lift the tank lid and slide the holder onto the overflow tube, the open pipe in the middle of most gravity-flush tanks. No tools are needed.

2. 02

   Route the refill water through it

   Step 2: Connect the small refill hose from the fill valve to the holder, so the stream that normally tops up the bowl after a flush passes through the tablet chamber first.

3. 03

   Every flush doses the bowl

   Step 3: As the tank refills, water flows over the tablet, picks up cleaner and drains down the overflow tube into the bowl. The tablet never sits loose in the tank water.

The patent describes a holding chamber at the overflow pipe. Fill water from the refill tube enters the chamber, contacts a cleaning substance (a tablet, gel or powder), and leaves through a discharge hole into the overflow pipe and on to the bowl. The stated aim is to keep chemicals away from the tank's mechanical parts while still delivering cleaner to the bowl on every flush.

Why this matters

Ordinary in-tank tablets dissolve in the whole tank of water. That turns the tank into a bath of cleaning chemicals that sits on the rubber flapper, the fill valve and the metal parts for hours between flushes. Plumbers have warned about this for decades. Plumbing & Mechanical magazine's long-running column on the blue toilet water problem describes water district tests in which flappers exposed to in-tank cleaners failed to seal, leading to silent leaks.

Happy Toilet Cleaner's answer is to move the tablet out of the tank water and into the stream that goes to the bowl. That is a simple, logical design, and it is what makes the product more than a gimmick.

What it does not change

The holder does not clean anything by itself. The cleaning comes entirely from the tablet you put in it, and how well that works depends on the tablet's chemistry, your water hardness and how often the toilet is flushed. Nor does it reach the inside of the rim, the outside of the bowl, the seat or the floor around the toilet.

Who it's for

Happy Toilet Cleaner suits people who like the idea of in-tank tablets but not the side effects. If you already buy tablets, it lets you keep that habit while protecting the parts that cause the most common toilet leaks. It also suits households where the bowl gets a ring between cleans: busy family bathrooms, guest toilets that are rarely used, holiday rentals and offices.

It is less useful if your toilet is spotless because you already clean it weekly, or if your stains come from hard water rather than everyday use.

Why Happy Toilet Cleaner appeals

Toilet cleaning is one of the least popular household jobs. A gadget that promises to do it on every flush, invented by a plumber, made in the USA and sold with a 90-day guarantee, is an easy sell. The price is modest, fitting takes minutes and there is nothing to plug in.

There is also a real plumbing argument, not just a convenience one. Flappers that warp or swell let water trickle into the bowl constantly. New York City's water department notes in its toilet leak guide that a leaking toilet can waste a large amount of water, and a worn flapper is one of the usual causes. Anything that slows flapper damage has value.

A typical setup

You lift the tank lid and look inside. In the middle is the overflow tube, with a small rubber hose clipped to it from the fill valve. You unclip that hose, slide the blue holder onto the overflow tube, connect the hose to the holder's inlet, drop a tablet in and replace the lid. Flush once and watch the tank refill: water should run through the holder and down the overflow tube. The brand says this takes about five minutes with no tools, which matches how simple the parts look.

Who gets the most value

Homes with several toilets that already use tablets get the most value, especially at the multi-buy prices. Landlords and holiday-let owners who want toilets to look fresh between visits may also find it worthwhile, as long as they fit it in toilets they are allowed to modify.

Who gets the least

People with high-end or Kohler toilets still under warranty, people with pressure-assist or tankless toilets, and anyone hoping to stop cleaning entirely will get the least.

What it will not do

It will not remove existing stains or limescale, clean under the rim, deodorise the room, fix a leaking flapper that is already damaged, or work without a tablet. It also will not stop you needing to clean the seat and outside of the toilet.

As a gift

The offer page pitches it as a gift for elderly parents and busy people. It can be a thoughtful one, but toilets vary, so it works best if you fit it yourself or check the tank first. Pair it with a pack of tablets the recipient is happy to keep buying.

• People who already use in-tank tablets and want to stop them eating the flapper and fill valve
• Busy households, rentals and guest bathrooms where the bowl tends to get a ring between cleans
• Older relatives or anyone who finds bending to scrub a toilet hard, as long as someone checks fit

Who should skip it

• Owners of Kohler toilets under warranty, unless they accept Kohler's in-tank cleaner warning
• Homes with pressure-assist, tankless, wall-hung or unusual dual-flush toilets
• Anyone expecting it to remove existing hard-water rings or end cleaning altogether
• Homes with pets or toddlers that drink from or play in the toilet, if you plan to use bleach tablets

How much does Happy Toilet Cleaner cost, and what's in the box?

Happy Toilet Cleaner cost $24.99 for one holder on the offer page on 3 October 2026, plus shipping, with three for $49.98 and five for $74.97, about $14.99 each. The brand store listed one at $24.99 and tablets from $18.99 for 12. The box holds the holder, a quarter-inch adjustable fill hose, a securing clip and one Ultra tablet, which the store says lasts three to four weeks.

According to the brand store, the box contains the holder, a ¼-inch adjustable fill hose, a securing clip and one Ultra cleaning tablet. The store says the tablet lasts three to four weeks.

• 

  The holder on its own

• 

  The retail box

• 

  The holder with its fill hose and clip

Specifications

Happy Toilet Cleaner price and bundles

On 3 October 2026 the Happy Toilet Cleaner offer page (opens Happy Toilet Cleaner in a new tab) listed these options:

The page lets you choose the standard holder, the Deuce for Kohler toilets, or a mix. The buy button showed the three-holder bundle at $49.98 by default, so check what is selected before paying.

The brand's own store

The Happy Toilet brand store, run by the same Gilbert, Arizona company, listed the holder at $24.99 against a compare-at price of $39.99 on the same day. It also offered two for $44.80, a buy 2, get 1 bundle for $49.95 and four for $63.96. It sold extras too:

What this means for you: prices are close. The offer page's five-holder bundle is the cheapest per holder we saw, at $14.99 each. The store is the place for tablets and for two-packs. The brand selling a toilet brush alongside a device that promises you will never scrub again says something about realistic expectations.

Running costs

At $18.99 for 12 Ultra tablets and three to four weeks per tablet, the brand's own tablets cost roughly $16 to $25 a year per toilet. Supermarket in-tank tablets vary widely in price, and the brand says you can use any of them. Add the one-off holder price and a three-toilet home is looking at about $50 up front plus tablets.

Is it good value?

As a one-off purchase of $15 to $25 that might save you a $10 to $20 flapper replacement and the water wasted by a slow leak, it is reasonable value for anyone who would use tablets anyway. As a replacement for cleaning, it is not, because you will still clean, and you add a tablet bill.

Who makes it

The patent lists Jerald Christopher Stanfield of Arizona as inventor. Local press in Gilbert, Arizona has covered Chris Stanfield and his wife Linda launching the product. The offer page says Chris is a licensed master plumber with more than 40 years' experience; another report we found gave a shorter figure, so treat the exact number as unverified. Two segments on ABC15's Sonoran Living show featured the product; at least one is listed under the show's sponsor content, which means it was paid placement rather than independent coverage.

How well does Happy Toilet Cleaner work?

Happy Toilet Cleaner should work well at keeping bowl water treated and keeping tablets away from tank parts, based on its design and owner reports. Every refill sends a little cleaner into the bowl, which slows the ring at the water line. It will struggle with hard-water limescale, which bleach tablets do little to dissolve, and with marks above the water line or under the rim.

Nobody on our team has fitted one, so this section is based on how the device is designed, what the patent describes, what owners report and what plumbing sources say about in-tank cleaners.

Where it should work well

• Keeping the bowl water treated. Every refill sends a little cleaner into the bowl, which slows the build-up of the brown or grey ring at the water line in a toilet flushed every day.
• Protecting tank parts. The tablet sits in its own chamber instead of in the tank, which should cut the time the flapper and fill valve spend in concentrated cleaner.
• Rarely used toilets. Guest toilets and holiday homes develop rings partly because water sits still. A dose of cleaner at the last flush may help.
• Easy upkeep. Changing a tablet is a matter of lifting the lid and dropping one in.

Where it will struggle

• Hard-water scale. Limescale rings are mineral deposits. Most bleach tablets do little to dissolve them; an acidic cleaner and a pumice stone or brush are the usual fix.
• Under the rim. Refill water from the overflow tube enters the bowl through the rim jets on many toilets, so some cleaner reaches the rim, but stubborn build-up there still needs a brush.
• Splashes and marks above the water. Nothing in the bowl water reaches them.
• Toilets flushed rarely. Fewer flushes mean fewer doses.
• Unusual tanks. If the holder cannot sit securely on your overflow tube, or the refill hose cannot reach, it will not work properly.

What owners say about using it

The offer page shows 103 reviews and a handful of testimonials. Owners describe easy installation, cleaner bowls and buying holders for every bathroom and for family members. One says tablets used to damage their tank plumbing and the holder fixed that. These are positive but brief and chosen by the seller, and none describes long-term use beyond a few months.

How long will it last?

The holder is a simple plastic part with no moving pieces, so it should outlast several tablets. The parts most likely to need attention are the small hose and clip. Bleach is hard on some plastics and rubbers over time, so check the hose occasionally. The brand sells an optional three-year warranty for $9.99, which suggests it expects the holder itself to last.

What a month might look like

In a family bathroom flushed many times a day, the tablet will see plenty of water and dissolve steadily. If the brand's three-to-four-week figure holds, you would add a new tablet about once a month. Between deeper cleans, the bowl water stays lightly treated, which should keep the ring at the water line fainter. A quick brush once a week deals with anything above it. That is a realistic picture: less scrubbing, not none.

Does it really protect the flapper?

The design keeps the tablet out of the tank water, which is the main source of flapper damage from tablets. Some cleaner can still find its way into the tank if the holder or hose leaks, or if dissolved tablet seeps out between flushes. The brand has not published test results showing flapper life with and without the holder, so we treat this as a sound idea rather than a proven result.

Are Happy Toilet Cleaner's claims true?

Happy Toilet Cleaner's core design claim is sound: every refill carries cleaner into the bowl. "Never scrub your toilet again" is overstated, since tablets slow staining but do not remove limescale or marks above the water line, and the brand's store sells a toilet brush. "Works with any tablet" is probably true if it fits. Savings claims such as "75% less product" are not supported.

"Automatically clean your toilet with every flush"

Partly true. Every refill does carry cleaner into the bowl. But that is a dose of cleaner in the water, not a scrub, and it will not clean what the water does not reach.

"Never scrub your toilet again"

Overstated. Tablets slow down staining; they do not remove limescale or marks above the water line. Most households will still need to clean the toilet, just perhaps less often. The brand's own store sells a toilet brush.

"Works with any cleaning tablet brand"

Probably true for most tablets, as long as the tablet fits in the chamber. Very large tablets or pucks may need breaking. The patent also mentions gels and powders.

"Uses 75% less cleaning product"

Unverified. Because the tablet sees water only during the refill instead of sitting in a full tank, it may well dissolve more slowly. The page gives no test data for the 75% figure.

"Protects your toilet from damage"

Plausible and the strongest claim. Loose tablets damaging tank parts is well documented. The holder keeps the tablet out of the tank water, which should help. It does not, however, change what Kohler's warranty says about in-tank cleaners.

"Installation takes just 5 minutes, no plumber needed"

Believable for a standard tank. The fitting is a clip and a hose. It may take longer if your overflow tube is an unusual size or your refill hose is short or brittle.

"Invented by a licensed master plumber with 40+ years of experience"

The inventor and patent are real. We could not verify the exact years of experience, and another report gave a shorter figure.

"Save $200+ on cleaning supplies and 24 hours a year"

Unverified and optimistic. Most people do not spend $200 a year cleaning one toilet, and you still buy tablets. Time saved depends on how often you cleaned before.

"Patented design" and "Made in the USA"

The patent, US 11,821,189, is real and was granted in November 2023 to the inventor. Made in the USA is the brand's claim, shown on the box; we did not see independent confirmation.

Claims scorecard

Is Happy Toilet Cleaner better than loose tablets or rim hangers?

If you already use in-tank tablets, yes: a holder that keeps them out of the tank water is a better way to use them. If you do not use tablets now, buying it means starting a habit with a running cost. Rim hangers and gel stamps never touch the tank and are cheap to try, though they are visible in the bowl. Regular cleaning is still needed either way.

Happy Toilet Cleaner vs loose tablets

This is the comparison that matters. If you are going to use in-tank tablets anyway, a holder that keeps them out of the tank water is a better way to do it. If you do not use tablets now, buying the holder means starting a new habit with a running cost.

Happy Toilet Cleaner vs rim hangers and gel stamps

Rim hangers and gel discs stuck inside the bowl release cleaner where the flush water enters, never touch the tank and are cheap to try. They can be messy to replace and are visible in the bowl. Many people find them a simpler first step.

Happy Toilet Cleaner vs a toilet with a self-cleaning glaze

Many newer toilets have smooth, stain-resistant glazes that make marks easier to rinse away. If you are replacing a toilet anyway, a better glaze does more for cleaning than any tablet. If you are keeping an older toilet, the holder is the cheaper option.

Happy Toilet Cleaner vs other tank tablet dispensers

Other tablet holders and dispensers exist, including older patented designs that use the overflow tube. If you prefer to compare, look at how the holder mounts, whether it fits your tank and whether it keeps the tablet out of the tank water. Happy Toilet's selling points are the plumber backstory, the made-in-USA claim and the Kohler-specific version.

Happy Toilet Cleaner vs regular cleaning

A quick brush and a squirt of bowl cleaner once or twice a week costs very little and cleans everything the holder cannot reach. The holder's role is to stretch the time between those cleans, not to replace them.

Other household products we have reviewed

If you are tidying up the house in other ways, our FixIts review covers reusable mouldable repair sticks, our HALT fire spray review looks at an aerosol for small fires, and our Campanelli stain remover review covers a laundry and fabric cleaner. For lighting, see our GuideLight review. You can browse the rest in our household gadgets category.

Is Happy Toilet Cleaner legit, and what should you check before buying?

Happy Toilet Cleaner is a real, patented product from a Gilbert, Arizona company, with a 90-day money-back guarantee on the offer page. Before buying, lift your tank lid: it is built for gravity-flush toilets with a standard overflow tube, and Kohler owners need the Deuce version. Kohler says any in-tank cleaner voids its toilet warranty, so check your warranty terms first.

Check your toilet type

Happy Toilet Cleaner is built for gravity-flush toilets with a standard overflow tube.

What to do: lift your tank lid before ordering. If you see a sealed tank inside the tank, a big round canister instead of a flapper, or no tank at all, it may not fit. If your toilet is a Kohler, choose the Deuce version.

Kohler and warranty terms

Kohler's installation documents, such as this Kohler installation guide, state that use of in-tank toilet cleaners will void the warranty and that chlorine (calcium hypochlorite) cleaners can seriously damage tank fittings. Happy Toilet sells a version for Kohler toilets, but we did not see anything from Kohler approving it.

What to do: if your toilet is new and under warranty, check your maker's terms first. If you go ahead, a non-chlorine tablet is the cautious choice.

Bleach and mixing cleaners

If you use bleach tablets, the bowl water contains bleach.

What to do: flush a few times and let the bowl clear before using any acidic or ammonia-based cleaner, because mixing bleach with them can release harmful gases. Remove the tablet before a deep clean if you prefer.

Pets and small children

Treated bowl water is not safe to drink.

What to do: keep the lid down if pets drink from the toilet or young children play near it. Store spare tablets out of reach.

Septic systems

The brand says eco-friendly tablets suit septic systems.

What to do: choose a tablet labelled septic-safe if you are on septic, and avoid constant heavy doses of bleach.

Hard water

Tablets do not dissolve thick limescale.

What to do: remove existing rings with a suitable descaler before fitting the holder, then let the holder help slow new staining.

Shipping and delivery

The single holder on the offer page adds shipping; the multi-buy bundles show free shipping. The FAQ heading about delivery times did not load for us.

What to do: check the delivery estimate and total at checkout, and keep the tracking email.

Old toilet parts

If your flapper or fill valve is already worn from years of loose tablets, the holder will not repair it.

What to do: do the food colouring leak test first. Replacing a flapper is cheap and usually a simple job.

Returns

The offer page shows a 90-day money-back guarantee.

What to do: keep the box and order confirmation, and read the returns terms on the offer page before fitting. Ask whether used holders and opened tablets are accepted.

How to buy Happy Toilet Cleaner the smart way

1. Check your tank and toilet brand, then order the right version on the Happy Toilet Cleaner order page (opens Happy Toilet Cleaner in a new tab).
2. Check which bundle is selected; the page showed three holders preselected.
3. Count your toilets: one holder per toilet, and the five-pack is the cheapest per holder.
4. Check the total with shipping on a single holder.
5. Decide which tablets you will use, and buy a septic-safe or non-chlorine type if that suits your home.
6. Keep your confirmation and note the 90-day window.
7. Fit one first and check it works before fitting the rest.

What do owners say, and how did we score Happy Toilet Cleaner?

Happy Toilet Cleaner scores 5.6 out of 10: claim accuracy 0.9, build durability 1.3, price competitiveness 1.3, usability 1.2 and owner satisfaction 0.9, each out of 2. The offer page shows 103 reviews and five short, all-positive testimonials praising easy installation and cleaner bowls. We found no Trustpilot profile and few independent owner reviews, and some coverage was sponsored.

Reviews on the page

The offer page shows 103 reviews and five testimonials. Owners praise easy installation, cleaner bowls and fewer tank problems, and several bought more for other bathrooms or relatives. The testimonials are short, all positive and selected by the seller.

Independent reviews

We found no Trustpilot profile for the brand on 3 October 2026, and few independent owner reviews. Search results include press releases and sponsored content written in review style, which are not independent. One summary we saw described mixed owner feedback, with some owners reporting fit problems on particular toilet models, but we could not check the underlying reviews.

Press and TV coverage

The Gilbert Sun News covered the couple behind the invention, which confirms the local story. The ABC15 Sonoran Living segments are a lifestyle show, and at least one sits in its sponsor section. A press release on a wire service is promotional too.

What we would test with Happy Toilet Cleaner in hand

If we test it ourselves, we will fit it to several common toilet models, time the installation, measure how long different tablets last, compare bowl staining against a toilet with no tablet and one with a loose tablet, and check the flapper after several months. We will update this review with the results.

How we scored Happy Toilet Cleaner

Every score on the site follows the five criteria on our how we test page.

The score would rise with published test results on flapper life and tablet use, independent owner reviews and clearer compatibility guidance.

What we did, and did not, do

We read the offer page, the brand store, the patent, a Kohler installation guide, plumbing trade coverage of in-tank cleaners and local press, all on 3 October 2026. Nobody on our team has used Happy Toilet Cleaner, and no figures here come from our own testing.

How to use Happy Toilet Cleaner for the best results

Clean the bowl thoroughly first, including any limescale ring, then lift the tank lid and unclip the existing refill hose from the overflow tube. Slide the holder onto the overflow tube, secure it and fit the hose, keeping the top of the tube open. Add a tablet that fits the chamber, check the lid closes without pressing on the holder, and flush to test.

1. Clean the bowl thoroughly first, including any limescale ring, so you start from a clean surface.
2. Turn off the water at the stop valve if you prefer, and lift the tank lid.
3. Unclip the existing refill hose from the overflow tube.
4. Slide the holder onto the overflow tube and secure it with the clip.
5. Connect the refill hose to the holder's inlet, adjusting the hose length so it does not kink.
6. Drop in a tablet, turn the water back on and flush.
7. Watch the refill: water should flow through the holder and down the overflow tube, and the tank should fill to its normal level.

Getting the fit right

The holder needs to sit firmly on the overflow tube without blocking the top of it. The top of the overflow tube is a safety route if the fill valve sticks, so water must still be able to drain into it. Make sure the tank lid closes without pressing on the holder.

Choosing tablets

Bleach tablets whiten and disinfect; non-bleach tablets with detergents are gentler on parts and septic systems. Blue dye tablets show you when the tablet is running low. Avoid tablets that say they must sit in the tank water to work.

Changing tablets

Check the holder every couple of weeks at first to see how fast your tablets dissolve. When the water stops showing colour, or the bowl starts to mark again, add a new tablet. Keep the next one by the toilet so you do not forget.

Cleaning around it

Keep a brush handy for the rim and above the water line. A quick weekly brush plus the holder should keep most bowls looking clean.

Holidays and rarely used toilets

Flush the toilet before you leave so the bowl holds fresh, treated water. A tablet dissolving slowly in a still chamber may release more cleaner than usual, so check the bowl when you return.

Step by step: checking for a leaking flapper

1. Put a few drops of food colouring in the tank water, not in the holder.
2. Do not flush for 15 to 30 minutes.
3. If colour appears in the bowl, the flapper is leaking and should be replaced.
4. Fit the holder after replacing the flapper, so the new flapper lasts longer.

Troubleshooting

What else do people ask about in-tank toilet cleaners?

Most questions are about damage and stains. In-tank tablets can degrade rubber flappers and seals, especially chlorine products, according to plumbing sources and toilet makers, which is why Kohler warns against them. Blue tablets used as directed are widely used, but never mix bleach tablets with other cleaners. Limescale rings need a descaling cleaner or white vinegar with a brush, or a toilet pumice stone.

Do in-tank tablets damage toilets?

They can. Concentrated cleaner sitting in the tank can degrade rubber flappers and seals, especially chlorine products, according to plumbing sources and toilet makers. That is why Kohler warns against them and why holders like this exist.

Are blue toilet tablets safe?

Used as directed and kept away from pets and children, they are widely used. The concern is mainly with tank parts, and with mixing bleach-based tablets with other cleaners.

How do I remove a limescale ring?

Turn off the water, flush to lower the level, and use a descaling toilet cleaner or white vinegar with a brush. A wet pumice stone made for toilets can lift stubborn rings from vitreous china. Rinse well before refitting a bleach tablet.

Why does my toilet keep getting a ring?

A ring forms where water meets air: minerals, bacteria and dirt collect at the line. Hard water, infrequent flushing and infrequent cleaning all make it worse.

What is a gravity-flush toilet?

The most common type: water in the tank drops into the bowl by gravity when a flapper or valve opens. Pressure-assist toilets use a sealed pressure vessel instead and are common in commercial buildings.

Is Happy Toilet Cleaner worth it?

For anyone who already uses in-tank tablets, yes, it is a cheap way to protect tank parts. For anyone hoping never to clean the toilet again, no: it helps keep the bowl fresher between cleans, but it does not replace a brush.

Does it work with dual-flush toilets?

Some dual-flush toilets have a separate overflow tube and refill hose and may work. Others use a central valve with a different design. Check inside your tank and contact the seller before ordering.

Can I use it with a toilet that has a canister flush valve?

Kohler toilets often use a canister-style valve, which is why Happy Toilet sells the Deuce version for them. For other makes with canister valves, ask the seller.

Will it work in an RV or boat toilet?

Most RV and marine toilets do not use a tank with an overflow tube, so the holder is not designed for them.

Can I move it to another toilet?

Yes. It clips on rather than being fixed, so you can take it off and fit it to another gravity-flush toilet with a similar overflow tube.

Does it make the water blue?

Only if you use a blue tablet. Clear and white tablets leave the water clear.

Can I use cleaning gels or powders instead of tablets?

The patent mentions gels and powders as possible cleaning substances. The brand mainly talks about tablets, so check with the seller before trying something else.

Frequently asked questions