How to use a chlorine float
Updated: 23 October 2026
You have a chlorine float in the box and a tub of tablets, and you want the order of work before anyone gets in the water. The float only wets the tablets. You still test, you start with the slots mostly closed, and you keep tablets off the liner, the cover, and the deck. This is how to use a chlorine float as steps, not a ranking. Which model to buy is on the [dosing float comparison](/hub/diy-supplies/dosing-float). Peter F. checked the stored listings, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
You have a chlorine float in the box and a tub of tablets, and you want the order of work before anyone gets in the water. The float only wets the tablets.
You have a chlorine float in the box and a tub of tablets, and you want the order of work before anyone gets in the water. The float only wets the tablets. You still test, you start with the slots mostly closed, and you keep tablets off the liner, the cover, and the deck. This is how to use a chlorine float as steps, not a ranking. Which model to buy is on the dosing float comparison. Peter F. checked the stored listings, not a lab. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Tablet size | Adjustable flow | UK review note | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  EduPlayte EduPlayte 5 inch float | n/a | Dosage ring | 1 review, no text | 10.0 | about £4.99 | View offer |
| Best value |  Steinbach Steinbach Mini 20 g float | 20 g | Ring disputed | Missing lid; ring spins | 8.8 | about £5.39 | View offer |
 Gre Gre FDP20 20 g float | 20 g | n/a | Holds tablets; rub mark | 8.6 | about £11.82 | View offer |
On this page
Before any tablet goes in
Put gloves on before you open the tablet tub. These tablets are usually trichlor, and the dust and the wet sludge irritate skin and eyes. Read the label on the tablets you own. The float does not have a dose of its own.
Use one chemical in the chamber. Do not add bromine to a chlorine float, and do not put shock, granules, calcium hypochlorite, or acid in with trichlor. Happy Hot Tubs’ dispenser sheet states the mixing ban. If you change chemical, empty the float, wash it outdoors, and keep the sludges apart. Wet tablets do not go back into the dry tub.
Check the size before you fill. A Steinbach or Gre mini is for 20 g tablets. If the tablet may not match, read chlorine tablet size for a floater. Pool Warehouse’s line of about two 200 g tablets per 32 m³ does not belong in a 20 g mini.
Fill, set, and place
Open the lid over a bucket or on a surface you can wash, not over the pool cover. Put in only as many tablets as the chamber is built for, and fewer on the first day if the label allows a range. Happy Hot Tubs’ 20 g dispenser starts with about three or four tablets rather than about seven. That chart is theirs. It is not the setting for a Steinbach Mini or a Gre FDP20.
Close the lid so it locks or screws. Two UK reviews of the Steinbach mini say the lid was missing. If yours is missing, use the returns route and do not swim with loose tablets. Set the ring mostly closed, then open one step only after a test. Place the float where the water moves, away from the skimmer, and do not add a second dose in the skimmer at the same time.
While people are in the water
Take the float out before anyone swims or sits in a hot tub. Premier Blue’s dial is about 1–3 ppm. Deep Blue’s 20 g label talks about 1–3 mg/l in a pool and 3–5 mg/l in a hot tub, with pH 7.2–7.6. Follow the tub you bought. Do not merge those ranges.
Keep the float closed and upright, off fabric, off the cover, and off the deck. A wet tablet bleaches what it touches. One United Kingdom review of the Gre float says it left a black mark where it rubbed a hot tub. Move a float that sits in one corner.
When the dose looks wrong
Test before you change the ring. If the reading is low and the slots were nearly shut, open one step and test again the next day. If the reading is high, close the ring or lift the float out, and do not add more tablets on top. Cyanuric acid from trichlor builds until you dilute with fresh water. A float cannot remove it.
If the ring will not turn, stop. Forcing it can crack the body or dump the tablets. That is a return. If irritation continues after a test that matches the label, or if acid and chlorine have been mixed, stop using the pool and get help. Fumes from a bad mix are an emergency. A let tub is not a garden-float job. Spa limits are on chlorine float for a hot tub.
Common questions
How do I fill it without touching the tablets?
Wear gloves, open the tub outdoors or over a washable surface, and tip or place the tablets straight into the chamber. Do not handle them with bare hands, and do not wipe your gloves on a towel you will use later. Close the tablet tub before you close the float.
Where do I set the ring on the first day?
Start mostly closed. You can open one step after the next day’s test, not on the afternoon you fill it. A chart that says three or four tablets and a numbered slot belongs to the dispenser it was written for, such as Happy Hot Tubs’ 20 g unit. It is not a universal setting for every float in this comparison. If your ring spins the whole base, do not force it.
How many tablets go in?
Only as many as that float is built to hold, and fewer at the start if the label gives you a range. A 20 g mini takes 20 g tablets. It does not take the about two tablets per 32 m³ line from a 200 g label. Overfilling a small chamber and opening every slot is how a paddling pool becomes harsh by the next morning.
What if the ring will not turn?
If the ring turns the whole float and the slots stay where they are, stop. That is the fault one UK reviewer reported on the Steinbach mini. Forcing the ring is not a fix this page describes. Contact the seller and use the returns route.
How do I know it is working?
Test the water the next day, with the kit you already use, and compare the result with the range on your tablet label. A pool label and a hot-tub label in this set do not share one number, so do not borrow a neighbour’s target. If the reading is in range with the ring mostly closed, leave it. If it is low, open one step. If it is high, close the ring or lift the float out.
Related pages
Sources
Public UK sources and the amazon.co.uk listings compared on this page. Updated 22.10.2026.
- HSE: HSG179, Managing health and safety in swimming pools (retrieved 22.10.2026)
- HSE: Swimming pools (retrieved 22.10.2026)
- HSE: HSG282, Control of legionella and other infectious agents in spa-pool systems (retrieved 22.10.2026)
- PWTAG: Code of Practice (retrieved 22.10.2026)
- PWTAG: Technical note 68, swimming pool chemicals (retrieved 22.10.2026)
- Pool Warehouse UK: chlorine tablets 5 kg (retrieved 22.10.2026)
- Consumer Rights Act 2015 (retrieved 22.10.2026)