CYA question

[davidgerman]

I’m having a small algae problem. I tested my water with an FAS-DPD kit. CYA was 100. For grins I tested again with a Clorox test strip, and it seems to have confirmed that reading. (See attached). However, the test strip says I am within desired range.

And CYA is the same as stabilizer, isn’t that correct?

Pool math says I need 3 gallons of liquid chlorine. Will that remove the slight green algae stains?

Thanks!

 

[Texas Splash]

David, if you see algae it's time for the SLAM Process. Adding a couple gallons of chlorine alone won't do the trick I'm afraid. Yes, CYA is the end-term for stabilizer or liquid conditioner. But don't trust the test strip. Trust your own TF-100 CYA test. If the CYA is at 90 or above, I would recommend exchanging some water BEFORE you begin the SLAM. Best to get the CYA down to at least 50 if possible so that you can maintain a lower SLAM FC level.

 

[Texas Splash]

Once you get the CYA lowered, refer to this chart for the proper FC level during the SLAM. Don't forget to lower the pH to about 7.2 before starting the SLAM.

 

[proavia]

If CYA test 90 or above, do the diluted CYA test
This should provide a better indication of how much water you need to drain/replace.

For CYA > 90ppm, repeat the test adjusting the procedure as follows:

1. Fill the mixing bottle to the lower mark (15 ml line) with pool water.
2. Continue filling the mixing bottle to the upper mark (30 ml line) with tap water.
3. Shake briefly to mix.
4. Pour off half of the contents of the mixing bottle, so it is again filled to the lower mark (15 ml line).
5. Continue the test normally from adding R-0013, but multiply the final result by two.

If you need to dilute the pool water further then apply these ratios:[7]

Pool water	Tap or distilled water	Multiply result by
1	1	2
1	2	3
1	4	5

Note that when doing a diluted test not only do you multiply the range of the test you multiply the error rate of the test, so results are a ballpark - not an absolute.

 

[davidgerman]

FYI…I am on a water well, if that makes a difference.

 

[Texas Splash]

I am on a water well, if that makes a difference.

It does from the standpoint we can assume you must have iron in the water. If you are one of those "one in a million" wells that do not, let us know, but iron is probably a concern. That said, when you get algae you must treat that first regardless. So go ahead and adjust the CYA by lowering it as best as you can. Once you have the CYA down, lower the pH to about 7.2 and go into the SLAM Process and refer to the chart above for your proper SLAM FC level. It may aggravate the iron and turn the pool brown, green, or cause staining or discoloration. Just don't be surprised. It's the iron reacting to the chlorine. Addressing those issues can come after the water is 100% algae-free and you have passed all 3 SLAM criteria.