Green on bottom of pool - solar cover affecting it?

[lynn4ever]

Hi. I am hoping you can all help. I have a 30' round above ground pool. About 12 days ago, we put a solar cover on to increase the temperature. Two days later, we noticed green spots on the bottom of the pool. We removed the cover and brought the water to our local pool store to be tested. Our numbers were way off, but after 2 visits and treatments and vacuuming up the green, we tested perfect levels with everything and the water was clear.

We bought our own test kit as well and our numbers matched the pool store's numbers.

We put the solar cover on last Thursday. I looked at the pool today and the green spots are returning. I did the quick daily test for pH and chlorine and both are fine. I can do the full battery of tests, but I am not sure what to do.

Did we maybe not get rid of all the algae the first time and it's just growing again? If so, how can we make sure to completely get rid of it?

Thank you!!

 

[karmabiker]

Welcome to TFP.

Take a look at the ABCs ABC's of Pool Water Chemistry and Pool School.

A good test kit is going to be critical to your success. There is an article in Pool School on recommended Test Kits (hopefully yours is one of these and you can just post numbers) or you can use the link to the TF-100 in my signature line.

Once you have a good set of test results we will be able to assist. Of particular interest is your CYA level, check out the section on Pool School concerning the CYA/CL relationship and how to SLAM your pool.