Green Water

[bjthon]

I don't close my pool during the winter. Yesterday I vacuumed the pool. The water was blue but it did need vacuuming. The FC was 0, so being that it was temperature was warming up, I added some bleach. The TA was 70, so brought it up to 100 overnight.

Today the water is GREEN! The pH was 8.2 (from adjusting the TA) so I used pH decreaser and it came down to 7.4. I decided to shock the pool and with a CYA of 25/30, I put bleach in and now have FC of 12. CC=0.

Am I doing the right thing to get the water clear? Thanks in advance!

 

[JasonLion]

That depends on what kind of green. Was it a clear transparent green, or was the pool at all murky or hazy?

 

[bjthon]

Hey, Jason Thanks for replying. It is clear transparent green.

 

[bjthon]

Jason - I just went out to take another look. From the deck, I can see to the bottom at the shallow end. However, I cannot see the bottom at the deep end. When I'm at the edge of the pool, I can see the bottom at the deep end.

 

[JasonLion]

From your description it is very likely to be metals coloring the water rather than algae. Metals in the water, typically iron or copper, can turn the water a clear transparent green, especially when the PH is going up for some other reason at about the same time.

It is possible for algae to tint the water green before the algae is really obviously visible. Though if that was the cause I would expect the FC level to be falling quickly, and I would expect that adding extra chlorine would clear it up immediately. Metals in the water will turn even more green if you add extra chlorine.

The treatment for metals turning the water green is to lower the PH, let the FC level come down to normal, and if it doesn't clear up fairly quickly, add a startup dose of sequestrant.

 

[bjthon]

So I should just let the FC fall from 12 to 2-3? This could take awhile without sunshine, right? Is that OK? The pH is about 7.4 right now. Should I lower it more? Not sure what sequestrant is???

 

[Richard320]

So I should just let the FC fall from 12 to 2-3? This could take awhile without sunshine, right? Is that OK? The pH is about 7.4 right now. Should I lower it more? Not sure what sequestrant is???

pool-school/metal%20stains

 

[bjthon]

Jason - just wondering how metals can get into the water? We orginially filled the pool with city water brought in. For the past 1 1/2 years I've been topping if off with our well water (which has low iron and copper) as well as rain water. Just wondering!

 

[JohnN]

Some trichlor tablets contain copper. Some algaecides also contain copper. The other possibility I know is a mineral system. Have you been using any of these? Just wondering, how do you know your well water has low metals? Did you actually have it tested?

 

[JasonLion]

Iron tends to come from well water. Copper is in some kinds of algaecide and is also put into the water by ionizers and mineral systems. Copper can also get into the water if the PH is way too low and you have a heater with a copper heat exchanger (which is common).

Iron turns the water yellow, which often looks green against a blue pool surface. Copper tends to turn the water a bright emerald green.

 

[bjthon]

Some trichlor tablets contain copper. Some algaecides also contain copper. The other possibility I know is a mineral system. Have you been using any of these? Just wondering, how do you know your well water has low metals? Did you actually have it tested?

Hi John ~ No, have not used any of items mentioned. Yes, I did have my water tested. Copper was <0.05 mg/l and iron < 0.10 mg/l - both below "not to exceed" levels.