Do I take CYA into consideration?

[chem geek]

Bob,

As for the second part of your question on how to avoid the high CYA and the issue of adding liquid chlorine (or bleach) to your pool every 2 days due to the Florida sun, you are correct that even with CYA you will probably lose around half of your FC level during the day due to sunlight. However, a little CYA goes a long way as shown in this graph. Even with 30 ppm CYA you get most of the potential savings and don't need to keep your chlorine level as high -- bottom line, this means you will need to add less chlorine each day (or every other day). On the plus side, you will not need to add base (soda ash; sodium carbonate; borax) frequently -- perhaps not at all.

Though adding chlorine each day or two is the simplest option, there are others as follows:

1) You can get a salt water chlorine generator (SWCG) system. This will use electricity plus salt in your pool (that you add initially) to generate chlorine almost continuously. There is an upfront captial cost, plus a smaller cost for electricity, and a maintenance cost when you need to replace the cell after some number of years.

2) You can get a pool cover that is opaque to UV (most are). This will significantly cut down your chlorine loss and will also save on heating costs (if any).

3) You can get an injection pump for putting liquid chlorine into your pool. This is not common, but there is at least one user on this forum doing this. See this thread, this thread, this thread and this thread.

4) Over the winter, let the rains dilute your pool. That's what I did when I had over 100 ppm CYA due to use of Tri-Chlor when I first got my pool (it only took one and a half seasons to get to 100 ppm CYA).

You are correct that with significant splash-out and with backwashing (if you have a sand or DE filter) you can end up diluting your pool water including its CYA (and TA and CH). You can still use Tri-Chlor in a feeder when you go away on trips (up to about a week) or when you need to add CYA.

Richard