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It's just a lower concentration of Polyquat. The dosage would be twice as high. As noted on the ProTeam website, "For those who are looking a strong algaecide at half the price, try Polyquat 30." If you compare their dosages for Polyquat 60: compared to Polyquat 30: you can see that the...

Welcome to TFP! :wave: If you've taken the NSPF CPO course, then you might want to read Certified Pool Operator (CPO) training -- What is not taught.

You've got substantial chlorine demand. You've got 50% chlorine demand in far less than 24 hours. That's huge. There is of course a large demand when dosing right after a soak, but after the bather waste is oxidized (mostly in 12 hours, but certainly after 24 hours) the chlorine demand should...

I had the Trade % wrong for the 8.25% bleach. I've corrected that in my post. It's 8.64%.

If you can, then yes. Better to be over mixed than under mixed. If there's some reason you can't run the pump that long, then don't. It's not a disaster.

Yeah, negative CSI is not a problem for vinyl. That's only for protecting the calcium carbonate in plaster and grout. Sorry I missed that. Metal corrosion isn't so dependent on CSI but rather on low pH that is the main problem.

So maybe you got behind in dosing. The 24-hour loss rate should be measured after you've dosed sufficiently for your prior soaks so that there is not a lot of residual chlorine demand left. If you did this right, then it looks like you may have biofilm or something else consuming a lot of...

Just keep in mind that the amount of chlorine in pools is many thousands of times more diluted than laundry bleach.

Note that one is usually adding the Polyquat for closing when the pool water is cold. It is slower to mix in cold water. It's a somewhat viscous polymer.

125,000. So you basically want to do a 1:10,000 dilution and then the ppm you measure is the Trade % for the chlorinating liquid so that's two 1:100 dilutions (1.28 fluid ounces out of one gallon or 0.48 teaspoons out of one cup). For 8.25% bleach where the 8.25% is the weight % of sodium...

If there is no carbon dioxide outgassing or anything else going on in the pool, then colder temperature has the pH rise while warmer temperature has the pH drop. So this tends to counteract the temperature change of CSI. So you can just see if that happens and only adjust the pH higher if you...

You didn't answer whether you had an ozonator. As I wrote, ozone reacts with chlorine so if you have a powerful ozonator you can easily lower 50% or more of the FC in 24 hours.

There may be very poor bottom circulation and you might consider pointing the return (there probably is only one for that sized pool) diagonally downward to create a swirling circulation that may move more chlorine to the bottom of the pool.

If you let the FC drop to around 15 ppm FC, you can try the OCLT again and you may be at <= 1 ppm FC loss. That would confirm that what you've been seeing was just variation/error due to the high FC level.

You could do that, but I'm very surprised that your test kit doesn't have a chlorine neutralizer as part of the TA test. Do you have access to hydrogen peroxide? If so, then you could use that to neutralize the chlorine in the sample. One drop (assuming 24 drops/ml) of 3% hydrogen peroxide in...

See this post for tables of breakdown for 12.5% chlorinating liquid and 8.25% bleach. This is for high-quality product. Some brands may break down more quickly if they are not careful in using water free of metals.

The above is for setting the proper goals, but if you wanted to translate an FC into the weight of chlorine gas which is how SWGs are rated, then use "chlorine gas" in the FC section or in the "Effects of adding chemicals" section. You obviously don't add any of that directly (you set a %...

Technically in quantitative chemistry one has the endpoint at the halfway point between the color before vs. after the endpoint. However, there is enough error in the test kits and for simplicity the rule is to keep adding drops when there is a color change and not count the last drop that...

The official accuracy for the Taylor tests, and the TF-100 is based on Taylor reagents, is +/- 1 drop or 10% of the reading whichever is greater. This is for absolute accuracy. The OCLT is more about relative accuracy since one uses the same reagents for measurements at night and in the...

For a hot tub if you have an ozonator the ozone will react with chlorine and will significantly increase the 24-hour chlorine demand with no bather load to 50% or more FC loss. With no ozonator in a hot spa a loss of 20-25% is more typical but if the water temperature is cooler then it could be...

You can add more thiosulfate drops to dechlorinate the water as part of the TA test. Taylor kits have that reagent and with high FC one can use more such drops.

Don't forget to use Dichlor for about one day a month in order to keep the CYA level up. Chlorine will oxidize the CYA in spas at roughly the rate of 5 ppm per month. You don't want the CYA to get too low or else the active chlorine level will get too high.

Technically, spa manufacturers say not to use Trichlor tabs in a spa. The reason is that with the hot water they dissolve too quickly unless you have a special feeder and they are acidic. You'd have to watch the chemistry and that's not something you can do while you are away. Probably the...

See this post for winterizing instructions from Buckman Labs, the makers of Polyquat. You do not want very high chlorine levels with Polyquat since chlorine will oxidize it. Having a moderately higher level (say, half-SLAM level so FC/CYA ratio of 20%) is OK, but the idea is that the Polyquat...

If you do, then your spa will become a bromine spa until your next water change. You can certainly do that if you want to -- up to you. Or if you want to keep it a chlorine spa you can have your SWG on for a short time each day to maintain a chlorine level, though it sounds like maybe you...

You can add it at any time.

Yes, you really don't need to test the borates. Just add the proper amount after each refill. It doesn't break down so should last through until the next water change and its exact level isn't important. You just want enough for decent pH buffering and 50 ppm is a good amount, but even 30 ppm...

FlowVis® Flow Meters do not need long straight pipe runs (unlike other flow meters). See Section 8 Installation in this manual showing that it can be installed right next to an elbow since it is not affected by flow stream disturbances.

This is a spa, not a pool. If the TA is truly at 25 ppm, I'd bring the TA up first using baking soda (the pH will not change much at all) and then lower the pH using acid. 40 grams of baking soda (sodium bicarbonate) and 7 grams of dry acid (sodium bisulfate) in your 225 gallon spa should get...

If you let the pool go over the winter then there are basically three things that could happen with regard to CYA. It could go down some from water dilution. It could go down a lot from bacterial conversion resulting in ammonia creating a huge chlorine demand upon opening. Or it could go down...