Added Clorox to Green Pool

[Ken]

I have a 25,000 gallon in ground pool. I'm in the same boat as a lot of frustrated pool owners where I have sunk over $500 in chemicals to try and cure my algae problem. After reading through quite a few of posts, I followed the some advise that was given. I added 7 gallons of regular strength Clorox last night. Pool looks a little better this morning but maybe that's being wishful after all these weeks of looking at green pool.
I brought a sample to the pool store this morning and here are my results:

FAC = 4
Water PH = 7.2
Total Alkalinity = 110
Calcium Hardness = 400
CYA =- 100
Total Dissolved Solids = 950

Please adivse, I'm so freaking frustrated trying to get this pool balanced I'm ready to fill the damn thing up with dirt and make it a big flower pot!

BTW - I've had this pool now for 8 years and this is the first time I'm having this problem. I switched from a DE filtering system last summer to a cartridge filtering system. Do you think that has any bearing on my problem??

HELP!

[Backglass]

Are you sure it's algae and not copper? Are you using algaecide?

[Ken]

yea...the algea has been growing back on the sides of the pool. i'll get it clear using the advise from the pool store...green out + tons of shock. then the water is clear for a few days (we've actually were able to swim a couple of times already). but after a few days you can see the growth start coming back on the sides and the bottom. went away this past weekend, but before i left i threw 4 bags of shock (trichlor based) in. when we retured on sunday evening the sides were green as can be but the water was clear. took my sample to the pool store on monday and had 0 FAC. so, on the advise of the pool store again, i dumped in 6 bags of shock monday night and brushed it down. next morning got up and pool looked didn't look any better. that's when i tried the clorox thing.....

[Ken]

and no, i haven't used any algaecide. just green out + shock, and yellow out + shock. not recently but in the course of trying to get my pool right.

[chem geeks]

To answer your question, yes, your switching from a DE filter that you probably regularly cleaned with pool water that caused dilution to a cartridge filter where you no longer remove pool water and refill with fresh is one key factor in your situation.

By no longer regularly diluting your pool water, the Cyanuric Acid (CYA) levels built up over time. You were probably using Trichlor tabs and for every 1 ppm Free Chlorine (FC) you add to your pool with such tabs, you also add 0.6 ppm CYA. The problem is that whereas the chlorine gets used up, the CYA does not and continues to build up unless you regularly have a lot of splash-out, backwash, drain/refill or other dilution of the pool water.

First you need to get rid of the algae in your pool and that will not be easy to do with chlorine alone given your high CYA level. Even if you did clear your current algae bloom, you would need to maintain an FC level of at least a minimum of 7 ppm in order to prevent algae. If you instead do a partial drain/refill of your pool to get your CYA level to 50 ppm, then you would only need a minimum FC level of 3.7 ppm. With a more normal CYA level of 30 ppm, you only need a minimum FC level of 2.2 ppm.

To prevent the buildup of CYA, you have several options. One is to switch to using bleach or chlorinating liquid as your source of chlorine. You could also use Cal-Hypo instead, but that will build up Calcium Hardness (CH) over time. For every 1 ppm of FC from Cal-Hypo you increase CH by 0.7 ppm as well.

Another option is to use Trichlor but also use a weekly maintenance dose of PolyQuat 60 algaecide. This can get expensive, but it will keep the algae away and is what most pool chemical manufacturers recommend in various "programs" of theirs. Sell you Trichlor with CYA in it, have it build up and require you to use an algaecide that they also happen to sell. You can keep a lower FC level with the algaecide -- probably around 3 ppm will do, but when the CYA gets far above 100 ppm then there are other problems to deal with (very high CYA levels may damage plaster/gunite).

You can, of course, regularly do a partial drain/refill to keep your CYA levels in check when using Trichlor.

Regardless of the option that you choose, you should invest in a good test kit such as the Taylor K-2006 kit you can get at the following links (and at some pool stores, but be careful since the K-2005 that some pool stores carry is not the same and cannot measure high chlorine levels accurately).

[Pool User]

thanks for the reply chem geek, your analysis is exactly correct! now i understand what's going on, you've switched the light bulb on.

i added another 8 gallons of clorox last night and my pool now looks 100% better, i can even see the drain now. i'm in the process of draining water from the pool now to try and lower the CYA level. i'm going to discontinue the use of the tablets and just move to using bleach. after re-adding water, i'll add more bleach and take my water sample to be tested. i'll post my water level readings later today.

thanks for your help!!

[Pool User]

thanks for the reply chem geek, your analysis is exactly correct! now i understand what's going on, you've switched the light bulb on.

i added another 8 gallons of clorox last night and my pool now looks 100% better, i can even see the drain now. i'm in the process of draining water from the pool now to try and lower the CYA level. i'm going to discontinue the use of the tablets and just move to using bleach. after re-adding water, i'll add more bleach and take my water sample to be tested. i'll post my water level readings later today.

thanks for your help!!

[Pool User]

Ok, here's the latest results as of this morning.

FAC = 7.0
PH = 7.2
TA = 120
Calcium Hardness = 400
CYA = 100
TDS = 1200

Pool is nice and blue, clear as can be! However, I still see some residual algae that's clinging to the walls and a little on the floor. I've tried to brush off but it will no come off. Any ideas??

I'm also tryng to drain pool water every night to try and bring down the CYA level. Is that the right thing to do?

Thanks again for any help!

[Buggsw]

Keep adding liquid chlorine to keep it at a high shock level throughout the day and night for at least 2 or 3 days. When it holds the high level overnight, you've shocked it enough.

Brush and vac daily and keep that pump going until this all clears up.

Yes, if you dump and refill regularly you should see some improvement in your CYA.

[sattori]

Have you tried adding muratic acid?
I have an above ground pool that was great on all test readings only the water was green, i mean shrek green. It was horrible took a friends advice and added 2 packs of muriatic acid (in garden section at home depot) $10 for a box of 2 packs.
added 1 pack and ran the filter and it was light green
added the 2nd pck the next day and ran filter and it was all better crystal clear.

After spending a ton on algaecide and shock, i was so glad something so cheap worked.