High Alkalinity No Fc

[carolynm]

I have a 15' 48" aboveground intex pool with sw generator. Last year I had crystal clear water all year. I decided to leave the pool up this winter and it stayed clear until about a month before I opened it -and then it turned into a green swamp.

I opened it by putting in a couple #'s of shock and starting up the SWG and cleaning the bottom of the pool, and adding 2#'s of stabilizer. I got the water to an aquagreen color and there it has stayed, I can't see the bottom of the pool I had an accurate ph test kit but was not trusting the chlorine test so I invested in a taylor kit.

I tested the water:

Fc=0

Alk=350

PH=7.2

So alkalinity is my problem. I tested my tapwater figuring I might just drain it and refill, but my tapwater has almost the same alkalinity (330).

Today I started treating the alkalinity with muriatic acid and aerating the pool. So far I have dosed 8 oz, after the first test the alk was down to 300 - I haven't tested the second time yet as it's just been an hour since I added the 2nd dose.

My question is: Can I start working on getting the pool clear by adding chlorine while I'm messing with the alkalinity or will I just be fighting a useless battle? Do I need to wait until I get my alkalinity to a tolerable range before I start adding more chlorine? It will probably take days before I get the alk to target range, and I don't want the pool to get worse while I'm doing that. I currently have my SWG turned off.

Suggestions?

Thanks

Carolyn

[waterbear]

So alkalinity is my problem. I tested my tapwater figuring I might just drain it and refill, but my tapwater has almost the same alkalinity (330).

Alkalinity is one of your problems, the other seems to be a bad algae bloom. The two are not interrelated. The high alkalinity will just make it hard to maintain your pH. It will alway be rising.

My question is: Can I start working on getting the pool clear by adding chlorine while I'm messing with the alkalinity or will I just be fighting a useless battle? Do I need to wait until I get my alkalinity to a tolerable range before I start adding more chlorine? It will probably take days before I get the alk to target range, and I don't want the pool to get worse while I'm doing that. I currently have my SWG turned off.

Suggestions?

Thanks

Carolyn

In a word, no. Lowering TA requires that you monitor pH. Killing algae requires high FC levels. High chlorine will cause the pH test to give false high readings because of a chemical interference between the chlorine and the indicator dye. Since you started lowering the TA might as well finish it up and then attack the algae with chlorine. On the other hand you can hold off on lowering the TA until you get the pool clear. Really a choice of 6 of one half a dozen of the other at this point since it is still a swamp.

Personally, I would clear the pool first and then work on water balance but it is your choice.

[carolynm]

Thanks for the reply. I've read and read and read this week. It was my understanding that it would be hard for the pool to maintain fc levels with the high alkalinity? Is that not correct? I would much rather get the pool clear, and deal with the alkalinity afterward but I thought that was WHY I'm dealing with the Alkalinity. I thought I needed to get the ph/alk balanced and then move to fc.

[waterbear]

Thanks for the reply. I've read and read and read this week. It was my understanding that it would be hard for the pool to maintain fc levels with the high alkalinity? Is that not correct? I would much rather get the pool clear, and deal with the alkalinity afterward but I thought that was WHY I'm dealing with the Alkalinity. I thought I needed to get the ph/alk balanced and then move to fc.

I think you are confusing pH with total alkalinity. While related they are different. High alkalinity can make it difficult to maintain the pH where you want but has no effect on FC levels. If there is NO CYA present then pH does have some impact on how well chlorine works but once there is CYA the pH effects on chlorine become moot. FWIW, it is probably a better idea to keep the pH on the high side rather than the low side when trying to clear a green pool (it favors the formation of monochloramine and slows the formation of some of the really nasty smelling disinfection byproducts).

If you were doing a fresh fill then you would balance the pH and TA but only after adding the normal dose of chlorine. For a green pool you would need to bring the chlorine to shock levels and therefore could not accurately test the pH so it would be impossible to lower the TA properly, which depends on knowing the pH.

Hope this has not confused you!