OK, new member here. I've been reading this forum (and just about everything else I can google) on treating algae. I've been dumping massive amounts of chlorine into my pool-swamp, and have seen a little improvement but not as much as I had hoped. FWIW, the algae seems to be just floating in the water, not clinging to the walls, or on the steps, so I hope that's a good sign.
Here are my numbers:
Pool type: White plaster
Size: appx 23,500 gallon
Filter: Sand (new Zeobest 8/1/08)
Cleaner: Barracuda G3
Pump: 1.5 HP StaRite
Run time (for now): 24/7
Baseline chem (before treatment):
I have a basic test kit (Taylor DPD, PH, TA), and also 5 way strips (PH, TC, FC, CH, TA, CYA). I know strips aren't the best, I just use them to verify my other numbers to see if they're in the same ballpark. I'm going to order a Taylor K-2006 on Monday, so I can get all my own numbers. Right now I have to rely on the pool store to tell me CH and CYA, much as I hate that. I *think* the CYA and CH numbers are close because they came from the PS and my test strip results are pretty much in line with them.
Anyway, the back story is that I've been fighting algae almost all summer, ever since the water temp got above 80 degrees, which was back in early June (we're in Phoenix, AZ). I'd been using trichlor tabs in the floater, and powdered trichlor for shocking. I never gave a thought to the CYA I was adding to the pool and wasn't testing for it myself because my test kit didn't cover it and I hate going to pool stores. I liked the trichlor powder and pucks because it kept the pH in line and always seemed to do the trick against the algae.
Of course, I got to the point that I couldn't get rid of the algae no matter what I did. So, I finally relented and went to the pool store to have them test my water and maybe give me some advice. When I did, of course, the number that jumped out was the CYA, which was close to 300!! Well, of course that means drain, but since it's summer, there's no way to drain a white plaster pool until the ambient temps are in the 60's or so, which won't be until November. I did a partial water swap (23,000 gallons and a $70 water bill later) by using a small pump and the garden hose. and got the CYA into the range I have now. That's when I started doing some research and found out about all the problems that CYA causes with pool chemistry, and I know that even after I do the drain I'll probably have enough residual CYA leaching out of the plaster that I won't have to add any (or very little) for some time.
After I did the water swap and got the CYA down a bit, I was able to shock with about 6 or 7 lbs. of cal hypo and that got the water back to cloudy blue. That's also when I decided to change the sand (5 yrs old) to zeobest, in hopes of clearing the water even faster. Even after doing that, and with running the filter 24/7 for a week, it never did clear up. So, I just kind of gave up for a while and let the pool go back to green, thinking I'd just let it stay that way until November when I could do a complete drain and refill. I was letting the filter run about 10 hours a day just to keep the water moving and filtered for floating stuff.
But after a few weeks, I couldn't stand the sight of "the swamp" anymore. So I did some research and found out lots of info on TFP and elsewhere, that basically said if you add enough chlorine it will eventually kill the algae. I found the "Pool Calculator" online, and Chemgeek's "Chlorine/CYA chart", so I have an idea of what I think I'm up against in terms of keeping the FC high enough above the CYA. Even if I don't get all the way to sparking, I'm OK with cloudy blue for now (we're done with swim season anyway) until I can drain. I just don't want to look out my window anymore and see a swamp.
So, I bought some 70% cal hypo 1 lb bags, and then also found a pool store that sells 4 1-gallon jugs of 12.5% liquid for $11 so I bought 5 cases (20 gallons) of that as well. Last night, before sundown, I adjusted my pH down to about 7.2, added 6 bags of the cal hypo, and after about 30 minutes, put in 3 bottles of the liquid. Checked the pool about an hour later (it was dark) but it looked like the green was gone but just cloudy.
This morning, the water was a cloudy light green, much better but still not blue or gray. I checked the pH, which was back to around 7.8, and the FC (using the dilution method, I had to go 20:1 to be able to read it on my DPD kit) which was at about 30. So I added about a quart of acid, and 2 more gallons of liquid chlor, and within about 30 minutes, the darker green cast came back. So I added 4 more gallons of liquid in hopes of getting some results, and had to leave for work.
Came home, no difference in the pool, still dark green. Checked the FC again using the dilution method, was still at 35-40. Added another 4 gallons of liquid. So in the last 24 hours, I've added enough **unstabilized** (won't make the CYA mistake again) chlorine to put about 70ppm chlorine the pool. That seems like that should have been more than enough to kill anything that was there, even if some of it was used up in the process.
I haven't tested for nitrates or metals. Since I can't see the bottom, there might be a fair amount of organic material down there (the cleaner has been out for quite a while since I've been superchlorinating), but is there anything else I'm missing?? Or do I just need more patience (and chlorine)?
Thanks for any help or suggestions!!!