dark green algae staining bottom of pool?

[CADIYPool]

Hi. My water is clear but I have what looks like algae staining the bottom of my pool. Please see attached photo. Since my water is clear, do you recommend a complete SLAM or is there another alternative? And if I do SLAM it, what is the max Cl level that is considered safe for swimming?

Here are my test results:
pH 7.3
TA 90
Ca 250
Cl 3
CYA 32

Taylor K2005 test kit.

Updated: I just swept the pool. There is a small grey/green/brown cloud that comes off the bottom when I sweep it.

thx!

 

[jblizzle]

Sounds like it could be algae so you should follow the ShockLevelAndMAINTAIN Process. It is safe to swim up to shock level, see the FC/CYA Chart, although best to focus on the SLAM.

One issue is that you do not have the appropriate chlorine test. You need to add the FAS-DPD Chlorine Test to your kit to have the equivalent of the recommended K-2006.

 

[CADIYPool]

Thanks. The new test kit is on order. How do I know if it is mustard algae and therefore requires the higher chlorine level?

 

[jblizzle]

Read the mustard algae article in Pool School. Does not sound like mustard algae to me. Besides you follow the normal SLAM process either way.