Also starting to acquire green / yellow alge on pool ways…
There’s the organics. You’re getting an algae bloom. You’re going to need to SLAM the pool water. That’s a method of shocking the pool that will kill the algae efficiently and effectively.
BUT, Your immediate problem is the CYA reading of 5 ppm. There isn’t enough stabilizer in the water to keep the sunlight from burning up the chlorine. Salt generators need 60-80 ppm of stabilizer (CYA). But for the SLAM process all you need is 30 - 40 ppm because the salt generator should be turned off during the process.
Once everything is killed and the water is clear you can turn the salt generator back on and raise the CYA level to the recommended amount.
CYA can be added to the pool in 2 different ways, dry stabilizer and liquid stabilizer.
If you use dry stabilizer you will need 4 pounds to raise the CYA level to approx. 35 ppm. The drawback here is the amount of time it takes to add dry stabilizer to the pool.
If you use liquid stabilizer you will need 168 ounces, or 1 gallon and 5 cups to bring the CYA level to approx. 35 ppm. With the liquid stabilizer you simply mix the stabilizer in a 5 gal bucket filled 2/3 full of water, then slowly pour the water/stabilizer mix in front of a return. The downside to liquid stabilizer is it’s more expensive than dry stabilizer.
Dry stabilizer needs to be fully dissolved in water, which usually means adding no more than a few ounces of stabilizer to a 5 gal bucket full of water and thoroughly dissolving it before adding to the pool.
An easier way to add it is to add al 4 lbs. to a sock, or cut the foot off of a pantyhose and put it all in there, then tie the sock/hose to a pole/plastic pipe and suspend it in front of a return. Either way of using this method will take days.
No matter which one you use, backwash the filter before starting because the filter must run continuously and can’t be backwashed during the process of adding stabilizer and for 48 hours afterward.
While you are raising the stabilizer level you are going to need to super chlorinate the pool water.
The chlorine level to SLAM a pool with 35 ppm of stabilizer is 14 ppm. And this level of chlorination needs to be maintained until the algae is completely killed.
You are gonna need a test kit that will show high chlorine levels to do this. The 2 most recommended kits are the Taylor K-2006 and the TF-100 FAS/DPD test kits.
Let me know if you’re interested in this process.
J