Dark Green Pool Water

[snf1694]

Hello I just opened my pool later than usual. pool has dark green water. worse than I have ever seen. Hooked up pump and I am going to put in usual chemicals including algaecide any other suggestions.

Thanks

Snf1694

[waterbear]

Hello I just opened my pool later than usual. pool has dark green water. worse than I have ever seen. Hooked up pump and I am going to put in usual chemicals including algaecide any other suggestions.

Thanks

Snf1694

Before you just $tart dumping in chemical$ how about testing the water so you know what and how much you need to add. Usually a green pool is quickly cleared with just unstabilized chlorine but if your CYA is very high you might need to drain some water and dilute it. Also if you closed the pool with normal CYA levels and they have dropped then you might have a very large chlorine demand initially from ammonia. testing can let you know what to expect.

[snf1694]

Okay so I tested the water and here are my results...

Free Chlorine = .5

pH = 6.8

Total Alkalinity = 80

Cyanuic Acid = 30-50

Thanks

Snf1694

[waterbear]

Okay so I tested the water and here are my results...

Free Chlorine = .5

pH = 6.8

Total Alkalinity = 80

Cyanuic Acid = 30-50

Thanks

Snf1694

Gonna make a guess here that you tested with strips which, unfortunately, are not very reliable.

About the only thing I would trust is that your FC is very low, not surprising with a green pool. Assuming the CYA is above 30 ppm then al you need to do to clear the pool is to bring the FC up to about 15 ppm AND KEEP IT THERE until the pool is clear, cleaning your filter as needed. this means testint and adding chlorine (liquid chlorine or bleach is your best bet for this0 SEVERAL times a day. You do not need algaecide. In fact, unless the algaecide is copper based it won't kill the algae but just inhibit it so the chlorine works better at killing it. With your normal CYA a sodium bromide or organic ammonia based algaecide won't give you any advantage either. Your low pH is a concern and is not unusual if you normally chlorinate with trichlor. IF your pool is vinyl start adding borax a half box at a time until you get the pH up before doing anything else. Your pH might actually be much lower than 6.8 since that is the lower limit that can really be tested by the phenol red indicator.

If you can get your water tested somewhere that uses liquid reagents. Then do yourself a favor and invest in a Taylor K-2006 test kit. It will save you a lot of money and problems in the long run.