Mold growing with crystal clear water??


TFP Expert
LifeTime Supporter
Jun 12, 2009
NW Ohio
There's really only two kits which will have the all of the tests required for us to give advice and one to follow our advice: the TF-100 from or a Taylor k-2006. You won't find these at most stores.

Unfortunately we have found test strips to be awful and unreliable and pool store testing is barely better. Quality pool care starts with quality numbers to work off of, that's why we harp so much on good testing. There isn't much we can do without it.


Gold Supporter
LifeTime Supporter
Jul 16, 2010
Portland, Oregon
Welcome to TFP!

Can you tell us more about your pool? You can put your pool information in your signature, then everyone can see it any time you post.

The store probably won't help you right now. I'm going to assume you're using test strips to test the water. Unfortunately those are junk. Pure, actual garbage. You can throw them out.

First things first, you need to read ABCs of Pool Water Chemistry.
Next, you need a proper test kit. See Test Kits Compared. The TF-100 is the best deal, and exactly what you need.
Understanding the CYA/FC relationship is of paramount importance. See FC/CYA Chart
Chances are that you need to perform the SLAM Process
Also, to make things easy we use PoolMath to determine what and how much to add to the pool for water chemistry.

Take some time to check out some videos on YouTube. You can begin with these, but there are lots more at the TFP chanel:

Yes- y’all are exactly right!! It’s those stupid strips!! I hate them- I literally just told my husband that it’s all just a big money scheme for them & that they’re not interested in trying to get our pool levels good- they’re trying to make us spend more money!! ??
Thank you so much- I’ll be ordering a testing kit, adding a signature to my account, and doing the reading & videos you suggested! Thanks again! ☺


Bronze Supporter
All due respect to @Donldson, but Saprolegnia grows underwater. This is the source of white water mold. I know, I had it earlier this summer.

To IKNAP, you can get rid of your pool mold using the SLAM Process. I did it earlier this summer. Works like a charm. Just remember, don't quit until the three criteria are met:
  • CC less than 0.5
  • Water is crystal clear
  • You pass OCLT
Be sure to put your foot down and get a good test kit before starting the SLAM.


TFP Expert
Mar 2, 2011
What does the substance look like?

There are several funky things that can grow on the liner.

Black algae is a type of bacteria that's actually bluish green.

Do you have a picture?

Does it brush off?