Copper in water - ok to use bleach?

[mccato]

I’ve read most of the posts on this forum about using bleach; and I think I’m ready to give that a try. I've been battling a chlorine "demand" with calcium based shock and dichlor (not at the same time, of course); and recently saw some green algae appearing in places. I've been putting 2 lbs of shock in my 16,000 gallon pool every day since June because the chlorine won't hold. The CYA reading was always in range (water tested once a week). Anyway, a couple of days ago I used a whole bottle of algaecide plus and a whole bottle of mustard algae killer at my pool company’s recommendation. So here’s my question: will the copper that the algaecides put in the water cause a problem if I shock with bleach? We got about 3 inches of rain last night, so the water has been diluted some.

[JohnT]

All algaecides aren't copper based. You really need some good numbers. In range doesn't say much. Pool stores will tell you CYA is low at 100, which is in reality way too high. Post some water chemistry numbers and how you got them and we can get you straightened out.

[Simmons99]

While you are having your water tested - also have them test for copper since you are worried - just don't buy anything. I saw a guy in the pool store this weekend with a similiar problem and they wouldn't let him out of there without over $100 in unnecessary chemicals.

[mccato]

OK, I've got some numbers here. I know that not all algaecides have copper in them, but the one that I used did (3.3% I believe). I don't have a reading on the copper, though, but the water was a light purple when it was tested. They just didn't have the necessary stuff to read the results, I guess. I put 4 lbs of dichlor in last night, and got the water sample this morning. Here's what the analysis says:

CYA 146
TC 8.5
FC 6
ph 6.6 (this was 7.8 3 days ago)
TA 69
Sat. Index -1.2

[Watermom]

Your most immediate concern is your ph level. How could it have been 7.8 three days ago and now at 6.6? Have you added any muriatic acid? Did you pull your water sample off the top of the pool after rain before your pump had been running and circulating the water? If it is indeed 6.6, you need to add some Borax ASAP. Readings below 7.0 are acidic and can damage your pool. Also, your cya is sky high at 146. We recommend 30-50. How long have you been using dichlor? Have you used any trichlor pucks? With cya that high, you have two choices. One - you can do a partial drain and lower it. In your case, you'ld probably have to do a partial drain several times. Choice two - live with cya that high, but as a result you'll have to run much higher than normal chlorine levels. I'm sure that is why you are having algae problems because pool stores don't seem to know to tell people that if your cya is really high, your chlorine level must be also or else you get algae. Take a look at the sticky at the top of the chlorine forum called "best guess table." No more trichlor or dichlor for you. Both will cause your cya to continue to climb. Since you don't report your calcium hardness level or tell what type of pool it is, I can't recommend using cal-hypo. Bleach is your best bet for your source of chlorine.

[mccato]

Thanks for the reply. Sorry that I left out some pertinent info. It's a vinyl pool, 16 x 32. All summer I've not been able to keep chlorine in it, despite shocking every Sunday with the recommended 2 pounds and shocking every day in between with 1 to 2 pounds. I've been using dichlor for 2 1/2 weeks; prior to that I used calcium based. I'm not sure at all how the pH could have dropped so much. All I put in was the 2 bottles of algaecide (one with copper) and a total of 6 pounds of dichlor. The pump has been running 24/7 since I put the algaecide in. I didn't get the water samples off the top - I got them from about 10 inches deep. I had about 4-5 pounds of balance pack 100, so I just put that in to raise the alkalinity. I've not used any trichlor pucks. I don't have the past test sheets, but the CYA has not been that high until recently. Could the dichlor have done that? As I said, I've put a ton of shock in this pool in the last 6 weeks. The total hardness (I guess that is calcium hardness?) is 340.

Should I wait until the copper level has dropped to put the bleach in? I plan on getting another reading tomorrow, but they use Alex and don't have a way to gauge the copper reading.I tested the ph just now with drops and it appears to be right at 7.2, but that's with the cheap tester. I will get a good one soon! Assuming that the demand has finally been met (which may not be a good assumption), do I still need to keep the chlorine high for a while to take care of the algae? I have not seen any more; but I don't know when a safe period of time is to assume that it's cleared up.

Thanks for the help!