Re: Do I really need a PhD in Chemistry to do this?
Borrowing a reply from Chem Geek. The important info about pucks that doesn't make my eyes cross is in red:
Your pucks have dissolved quickly, since they were placed in the skimmer. In a floater they last a week or more. If you keep pucks in the skimmer you must run the filter 24/7 or remove the pucks when the skimmer is off. When the pump is off the water in the skimmer becomes corrosive over time due to the pucks sitting there releasing chlorine with no where for it to go. This can cause damage to the skimmer, skimmer basket, and plumbing.
Most people don't have to add CYA once it is at the correct level unless they routinely replace a lot of water through splashout and backwashing. There are a few who for some reason have their CYA disappear over the winter or let the chlorine sit at 0 for too long and bacteria in the water causes ammonia to form which in turn eats the CYA.
Borrowing a reply from Chem Geek. The important info about pucks that doesn't make my eyes cross is in red:
As you can see, the CYA can really add up. Splash out and backwashing may have kept yours in check, but we won't really know until we have a good test result.chem geek said:Trichlor is 91.5% available chlorine -- don't forget it has THREE chlorine attached to it and each produces a hypochlorous acid molecule. The molecular weight of Trichlor is 232.4103 g/mole while that of chlorine gas (which is how all chlorine is measured relative to) is 70.906 so 3*(70.906/232.4103) = 91.5%. Cyanuric Acid (CYA) has a molecular weight of 129.075 g/mole. So Trichlor is 129.075 / 232.4103 = 55.5% CYA by weight. These add up to more than 100% because chlorine is measured relative to chlorine gas, not to a single chlorine atom or to hypochlorous acid.
The way to look at it is that Trichlor does the following:
Trichlor + 3 Water --> CYA + 3 Chlorine (hypochlorous acid)
The 3" pucks unfortunately vary in weight being 6, 7 or 8 ounces (there are also 1" 3-ounce tabs and 1/2" 1-ounce tabs). If I assume 8-ounce pucks, then one in 10,000 gallons adds 5.5 ppm FC and 3.3 ppm CYA. The general rule regardless of puck weight or size is that for every 1 ppm FC you add using Trichlor, you also increase CYA by about 0.6 ppm (note that 55.5% / 91.5% = 0.61).
Richard
Your pucks have dissolved quickly, since they were placed in the skimmer. In a floater they last a week or more. If you keep pucks in the skimmer you must run the filter 24/7 or remove the pucks when the skimmer is off. When the pump is off the water in the skimmer becomes corrosive over time due to the pucks sitting there releasing chlorine with no where for it to go. This can cause damage to the skimmer, skimmer basket, and plumbing.
Most people don't have to add CYA once it is at the correct level unless they routinely replace a lot of water through splashout and backwashing. There are a few who for some reason have their CYA disappear over the winter or let the chlorine sit at 0 for too long and bacteria in the water causes ammonia to form which in turn eats the CYA.