California Draught, too much CYA, cloudy pool.

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Thehobe

Active member
Sep 22, 2014
35
Los Altos, CA
I switched from 3" tablets last year due to high CYA levels. I switched to Calcium Hypochlorite (shock) that results in keeping the algae at bay but the calcium, I assume clouds the pool. This year I have switched to liquid chlorine (for about 1 month now) but because of the high CYA levels, I have been having a problem keeping the chlorine levels constant.
Questions:
1) is it the calcium causing the cloudiness (because pre-mixing it never results in a clear additive.
2) My 25,000 gallon pool/100 gallon attached hot tub is taking a gallon a day of liquid, 10% Sodium Hypochlorite
3) does TFP believe in algaecide and/or NoPhos products?

Until the water flows from the skies again, I do not want to dump half of the pool water and have Jerry Brown showing up at my door with a big fine!

The CYA level is at about 90
All other chemical numbers are in their normal range

I have found 10% KemTek 2 gallon packs on sale at Orchard Supply Hardware for $4.95, a great price.

Chemistry is under control using high amounts of Chlorine and covering the pool day and night. The temp has risen to 86°F

Thehobe
 
That's too much chlorine usage. That and cloudiness points to a nascent algae bloom. You're managing to hold it in check, but you're seeing the bleached carcasses of dead algae which is clouding things. Let up on the bleach for two days and you'll have a nice green swamp going.

The bad news is that to get ahead of it, you'll need to raise FC to 35 (shock level for 90) and keep it up there for a few days. Or replace some water to lower the CYA and raise it to shock level for that CYA level. Neither choice is cheap or pleasant. We call the process Shock Level And Maintain.

There is a product that destroys CYA, but the results haven't been too good so far and they want lower FC than you need to stay ungreen. So if you let FC drop to destroy the CYA, your pool turns green and you end up using as much bleach to kill it all as you would have if you'd left it where it was.

Removing phosphates would starve the algae, but the manufacturer even cautions against adding it to a pool with algae. It'll look like milk soon after you add it and gum up your filter. Read the last line of the instructions. The pool store tends to ignore that in order to make the sale or something...
 
Your chlorine input (FC) is totally dependent upon your "current" CYA at that time. As Richard noted above, it your CYA is still 90, then your SLAM FC level would be 35. If you drain some of your water and lower the CYA, then you would use a little less chlorine (lower SLAM FC). See the Chlorine/CYA chart link below for examples.
 
We are in the same area and I am putting in a little less than 0.75 ppm per day right now. Extinction is less than 15% but I am using pool cover so that helps even with a CYA of 80 ppm and 5 ppm FC target.
 
I am also using a pool cover day and night, adding 1 Gal a night of KemTek 10% to keep the level at about 3-5 ppm. Pool is 18' x 38' as well with a 7.5' deep end; I figure about 25,000 gal. I found KemTek at Orchard Supply on sale for $5/2 Gal and bought about 50 gal to be used in the next 1-3 months. This sounds pretty close to what you are using.
I keep getting small outbreak spots of algae on the walls, I assume because the plaster is showing signs of age.
 
Thehobe said:
I am also using a pool cover day and night, adding 1 Gal a night of KemTek 10% to keep the level at about 3-5 ppm. Pool is 18' x 38' as well with a 7.5' deep end; I figure about 25,000 gal. I found KemTek at Orchard Supply on sale for $5/2 Gal and bought about 50 gal to be used in the next 1-3 months. This sounds pretty close to what you are using.
I keep getting small outbreak spots of algae on the walls, I assume because the plaster is showing signs of age.
Click to expand...

You are adding 4ppm of chlorine a day to the pool. That is at the high end of normal usage for some pools in the summer. Algae showing up in spots and the amount of chlorine you are going through tells me you need to complete the SLAM process.
 
Thehobe said:
I am also using a pool cover day and night, adding 1 Gal a night of KemTek 10% to keep the level at about 3-5 ppm. Pool is 18' x 38' as well with a 7.5' deep end; I figure about 25,000 gal. I found KemTek at Orchard Supply on sale for $5/2 Gal and bought about 50 gal to be used in the next 1-3 months. This sounds pretty close to what you are using.
I keep getting small outbreak spots of algae on the walls, I assume because the plaster is showing signs of age.
Click to expand...

Is your cover clear or blue? Clear allows more UV into the water and will break down more FC despite being covered.
 
I bought a long lasting cover (7 year) but it is translucent but not blue. I have been fearful of the potential negative effects of the "clear" cover but did not know the extent. I have wondered why covers tend to be blue. Could chlorine be the reason...maybe somewhat but chlorine loss is still much lower with the cover on than off. I will eventually do a slam but probably when water becomes more available. I'm just trying to do my part for California.
How long does one typically have to keep the FC up to do a complete SLAM?
 

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I have had both colored and clear covers and never noticed much of a difference in FC use. Possibly because my clear cover didn't really stay "clear" for very long. Eventually it turned a foggy translucent with salt residue.
 
There isn't any specific time span a SLAM can take. There are many factors that are unique to each pool and a lot depends on how precise one follows the SLAM procedure. Some pools are cleared in 2 days others take 3 weeks. The SLAMs that take a long time seem to be the ones which the process is not followed as described.

A SLAM can be completed without losing any water, it's just going to take extra chlorine. Many SWG pools have needed to be SLAMmed lately and most of them have the CYA in the 60-80 range.

One thing I would suggest is to remove the lights from their niches and check for algae.
 
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