Green, cloudy and foamy is no way to go through life, son

[davidb]

My 20,000 gal inground pool is generally slow to clear but this year has been particularly bad. TC on a strip appeared high, but FC was 0, even after 3 x 1 lb bags of shock. After finding this site, I am now seeing progress - quit the shock and found 12% liquid hypochlorite at BJ's ($3/gal). 4 gallons x 2 days of this later, FC is measurable and I even see hints of clearing.

My question regards the persistant foaming - looks like laundry day. Should I worry about this now, or wait until pool clears and FC is stable?

[CarlD]

The foaming is probably from something else you through in. You'll need to keep your FC high until it's all gone.
Be sure to run your filter 24/7 and backwash whenever the pressure rises by, oh, say 5psi.

You'll need to get proper test #s. If you don't have a decent kit, take a sample to a pool store and ask them to test it. You don't need to buy anything...we'll give you our best advice when we see the results.
Is your pool vinyl or concrete?
What size pump and filter and what type of filter do you have?

I opened to green slime this season as well, and my pool is about as big as yours. I immediately dumped in 4 gallons of 12.5% LC all at once (I don't care if it bleaches my old and ugly liner). 24 hours later the water was cloudy, but blue. Then it was just a matter of filtering all the crud out.

Carl

[Watermom]

Did you add any type of algaecide? Many of them will cause foaming.

[davidb]

As of this moment: Total hardness 100; TC 5; FC 3; pH 6.8, Total alkalinity 120; CA 0.

I have not thrown in anything besides shock (solid and liquid). I had a pool service open the pool and I don't think they put in algaecide, but I will ask tomorrow.

Vinyl side pool, sand filter, sorry I don't know it or pump size.

I have cyanuric acid but I was going to wait until FC is stable before adding.

[Watermom]

Have you tested the CYA level yet? Don't add any until you do test. You don't want to take a chance on getting it too high. Without knowing it, we can't really advise you how high to take the chlorine. I guess for now, shock the chlorine up to about 15ppm and try and keep it there. Test as many times per day as you can and each time add enough bleach to get the cl back to 15. There is no such thing as testing and dosing too often when you are fighting algae. The more often you do it, the faster you'll clear it up. When you report the CYA level, we'll tweak the recommended shock level for your pool. In a 20K pool, each gallon of 12.5% chlorine will add about 6ppm of cl.

Add some 20 Mule Team Borax (laundry aisle at Walmart) slowly to the skimmer while the pump is running, breaking up any clumps. I'd start with a box. After 2 or 3 hours, retest pH and if it is still below 7.0, add another box. You need to get the pH above 7.0 ASAP. Readings below 7.0 are acidic and can damage your liner.

Carl recommended that you get a good testkit. We recommend the Taylor K-2006 or 2006C which is the same kit with larger quantities of some of the most used reagents. If you order it through the Amazon link in my signature below, the Pool Forum makes a little money on the sale to help keep the forum online. Only order if the seller is Amato Industries. Some other sellers are substituting the K-2005 which you do NOT want.

Your hardness is ok (you don't actually need calcium in a vinyl pool), your alk is ok. Good luck and keep us posted how things are going. My guess is that your pool service will tell you tomorrow that they did add some type of algaecide which is causing the foaming. Also, post that CYA level when you get it.

EDIT --- I just noticed that you said your CA is 0. I'm assuming that you meant that your CYA is 0. If that is correct, then go ahead and add some stabilizer, but put it in a sock in front of a return jet instead of adding it to the skimmer. You'll most likely be backwashing frequently, so if you add it to the skimmer, it will get backwashed out. Give the sock a little squeeze once in awhile to help it dissolve faster. Aim for an initial reading of about 30ppm. You can always add more later if needed, but hard to remove if you get too much in there.

[davidb]

Thanks for the detailed reply. Sorry, yes CYA is 0, not CA. I will do the sock trick, add Borax, and keep chlorine high.

Yep, pool service did add algaecide!