Lost of CYA

[simonoaks]

Hi,

As I am in Florida, I pretty much maintain pool all year round. I did slack off a bit during winter (DEc and Jan) , but always maintained FC at 6ppm and PH at 7.5 .

Anyway, in March I did full test and found CYA was at zero (I guess due to lots of rain over the previous 6 months)

I raised it back up to 75 and all was well.

I have noticed FC has dropped over the last 5 weeks from a steady 7 to now 4. I initially thought is was just because way more sun was getting on the pool as the summer draws in, so increased SWG to 65% and increased pump run from 6 to 8 hours.

I just tested and FC is at 4, so it is not holding. So I decided to check CYA again and it is at 30. We have had a couple of big storms since March and also, it has been mainly super hot and dry so I am filling the pool about 4 inches per week, because of evaporation, but can you tell me what else may cause a 40ppm CYA drop in 3 months , and what tests I can do to figure out what is going on. OR is this just normal, based on the rain and the large amounts of pool refills. thx.

Off to Leslie's pool store now to go buy the 172oz of liquid stabilizer the pool math table says I need....... It gets very expensive maintaining CYA lol

 

[Texas Splash]

Buy the granular stabilizer at Wal-Mart for about $16 per jug (4 lbs). Not the "liquid gold" unless you really want to. The granular works just as well. A significant amount of rain and water exchange will reduce CYA. Evaporation won't. So with a few months of heavy rains it's possible. But aside from a very minor (normal) amount of CYA loss each month, usually CYA loss is related to water loss/exchange.

 

[JVTrain]

Rain amounts in Florida can certainly contribute to CYA being lost, if water is going out of an overflow. CYA is not lost to evaporation as it does not evaporate, just the water does. CYA will slowly decay over time in the presence of FC. Higher FC levels tend to make the CYA decay faster. This does occur very slowly however. If you're continuing to lose CYA because of overflow during heavy rains, you could supplement with trichlor tablets occasionally to bring CYA up. Also... stick to the granular CYA if you can. It's much cheaper than liquid CYA, unless you're dead set on the convenience of liquid.

 

[simonoaks]

Ok thanks.

The pool has not flooded over , and if it is not diluting each time I fill the pool each week, then is it normal to drop 50ppm in 3 months at fc 7-8 ?

If not, what are the causes of cya loss and how would I test for it?

I have only ever used liquid , what do you do with solid stabalizer, just pour it in like you do salt / baking soda/ calcium etc ?

Thx

 

[Texas Splash]

Water exchange or a leak has to be the reason. Your FC level won't have anything to do with it other than a minimal 3-5 ppm normal monthly loss. Do you have an auto-fill?

To increase CYA via granular stabilizer, place the required amount as calculated by the Poolmath calculator into a white sock and place in the poolside skimmer basket. For those concerned about suction flow to the pump, suspending the sock near a return jet or from a floating device will also suffice. Best never to allow undissolved granules to rest directly against the pool surface. Squeeze the sock periodically to help it dissipate. Once dissolved, consider your CYA adjusted to that programmed (target) level. CYA test readings should show a rise in 24-48 hours, however some pools may experience a longer delay to fully register. Best to confirm final CYA in about 5-7 days before adding any more stabilizer/conditioner.

 

[simonoaks]

I so not have auto fill. I lose about 3 inches per week, is that not normal in 85 degree heat and low humidity?

How would I test for a leak ?

I just thought, I do sometimes leave the hose running too long and it over fills by 4 inches then self levels back to normal, could that cause it ?

I guess I will need several socks, as I will need to add 4lb, to my 10k pool to raise it from under 30 ppm to 80 ?

 

[Texas Splash]

3 inches seems like a bit much. The "bucket test" as noted on the TFP Pool School - Leak Detection is one way we check to see if we are having any abnormal water loss. You might try that first. Overfilling your pool would do it too. Not as quickly, but in time it would add up I'm sure. You can hang more than one sock of stabilizer in the water at once if needed. That might help you as well.

 

[simonoaks]

I read the article. I have a lot of decorative tiles around the top of the pool that have grout missing inbeteen them , can water leak from there?

With the stabalizer, can you not disolve it by stirring it into a large bucket pool water and then pouring that liquid in ?

 

[Propbndr]

With the stabalizer, can you not disolve it by stirring it into a large bucket pool water and then pouring that liquid in ?

Been there, tried that. Stabilizer is slow to dissolve so you'll be stirring for hours. I tried using a paint mixer attached to my power drill and finally gave up. The water in the bucket will get supersaturated with cya which will prevent more from dissolving. Then you run the risk of pouring the undissolved cya granules into the pool. I find it is best to use the sock method in front of a return jet..

 

[simonoaks]

Ok, so I put 5lb of stabalizer in 3 socks and left them over the return jet. It was taking a while so I just got in the pool and kneaded then like you would with dough and the whole lot was dissolved in 15 mins

 

[JVTrain]

Great to get the fingers limbered up!