Help....cloudy pool with stains and algae

I'm new here! Trying to figure out what to do to get everything balanced and clear! I have bought one of those fancy kits that you guys recommended and it came in today! My first test results were as follows:

Chlorine 18.5
CC 0
PH 7.2
alkalinity: 100
CYA 50
I couldn't figure out how to read the calcium because there was no color change. My last pool store reading was a little low.

I have been running the pump 24/7.... I have a sand filter

fiberglass pool 20,000 gallons.

Last week we had the beginning of an algae bloom so I shocked it. I have been draining pool little by little to get CYA down because last reading from pool store was 72. I got the algae bloom because I did a stain removal without adding the polyquat algecide. They failed to tell me to do that at pool store. Now stain is back more than ever! I have ordered all the stuff that ya'll recommended on stain removing. I'm afraid to do it because it is so hot here and I dont want to risk another algae bloom! Right now just want clear water even if it means swimming in a Tea stained pool! I hope I posted this right. Thanks for any help!!!!!

Fiberglass seems to be especially sensitive to iron stains. Are you on well water? Do you have a water softener?

Otherwise, your chemistry looks very good. Don't worry too much about the calcium right now -- it's not critical on an FG pool. But, when you get a chance, you might want to watch the Taylor calcium video - Taylor-K2006-Videos-on-YouTube

Using the polyquat (www.poolsolutions.com/polyquat.html) while you remove stains, allows you to operate with lower chlorine, without risking algae. You'll need both polyquat and HEDP to clear up the stains. But first, we need to figure out how the iron is getting into your pool.

Don't worry about your CYA -- it's fine!

If you want to do so, you can go ahead and treat your pool with borax -- maintaining a 60 ppm borate will make your pool algae 'resistant'. For a 20K pool, you'll need to add about 19 boxes of borax + 12 gallons of muriatic acid. That's over $100 . . . but the borax will remain permanently, except for what's lost by splashout or backwashing. If you *do* decide to add borax, add acid FIRST and then add the borax. That way your pH will stay low, which will help prevent stains. Actually, if you add 1/2 of the acid at a time, it will likely 'lift' the iron off the pool. Do *NOT* leave it low; add 1/3 of the borax, and then add more 1 box at a time til your pH reaches 7.4.

In fact, you can do it all at once:
1. Let your chlorine drop to below 5 ppm and backwash your filter completely.
2. Add 1 full quart of 60% polyquat.
3. Add a dose of HEDP (dose depends on which product you buy -- concentrations vary)
4. Add 1/2 of your muriatic acid.
5. Brush the pool and wait 2 hours.
6. Add 1/4 of the borax.
7. Wait 12-24 hours.
8. Add borax till pH reaches 7.4
9. Add 2/3 of the remaining acid.
10. Add 1/3 of the remaining borax
11. Brush again.
12a. If the pool is stain-free, continue adding borax till you reach 7.4. --OR--
12b. If some stains remain, wait 12-24 hours before adding borax.
13. Once you have reached 7.4, add 1 box of borax every 24 hours till your pH reaches 7.8 - 8.0
14. At that point, add more acid, till you get to 7.4, before adding more borax.
15. Shoot for a final pH around 7.6 - 7.8
16. During this period, maintain chlorine levels of 1 - 3 ppm, but add chlorine ONLY in small doses via the skimmer AND add 1/2 dose of polyquat every 2 - 3 days.
17. Once all the borax has been added, and the pH is 7.6 - 7.8, your stains will (hopefully) be gone. However, it is very IMPORTANT for you to understand that most of the iron is STILL in the water; you've just moved it from the walls, to the pool water.
18. Using chlorine added in SMALL doses via the skimmer (tabs?), gradually raise your chlorine levels to 10 ppm
19. If you have not had to backwash before, do so at this point regardless of pressure.

IMPORTANT NOTES:
(a) read the muriatic acid page, in my signature, before handling acid.
(b) do NOT dump the borax into the pool; it will clump and can remain for days.
(c) DO add the borax slowly to the skimmer, while the pump is on, being careful NOT to choke the skimmer.
(d) your filter needs to be functioning WELL for this process to work. Buy some DE powder to test it. Add a coffee can full to the skimmer. If no DE shoots out into the pool, your sand filter is working well. However, if you add DE to the skimmer, once you start the process above, the DE will help collect the iron and remove it from the pool. A good dose would be 1 - 2 coffee cans full for a 24" (300#) sand filter. You'll need to replace it after each backwash.

Thanks so much for the help.

I am not on well water, and I have no idea where the iron is coming from! We inherited this pool and it was closed for 8 years before we opened it! It had the stains on it then. It is an old pool, but has a new filter. There is no ladder or anything rusting that I can see.

Now I am probably going to sound stupid, but is the muriatic acid suppose to remove stains or adjust ph or both? I have a bunch of asorbic acid already so I did not know if I could use it for something? I also have Jack Magics pink stuff... I think that is the HEDP?

Do you think the water is cloudy because there is still some algae lurking?

+ Jack's Magic Pink = HEDP

+ Ascorbic acid can remove iron; but you MUST have the polyquat to use it. Chlorine destroys ascorbic acid almost instantly, so you have to dechlorinate your pool to use it effectively.

+ Muriatic acid lowers pH, but low pH + HEDP *tends* to dissolve iron. However, ascorbic acid WILL dissolve iron stains, so since you have that, you can plan to use it.

+ Re: cloudy water -- test your filter with DE, per note #d above. Your filter may need service. If so, that needs to be fixed before you try to remove stains.

+ Re: iron source -- other possibilities include low grade pool salt, if you have added salt; OLD iron water distribution lines; iron lines in VERY old swimming pools (pre 70's). Do any of these apply to you?