Adjust TA when chlorine very, very high?

[chem geek]

Patience, patience, patience. Yes, it can take some time to kill off a lot of algae. At least it's getting better, so stick with it. With your CYA of 50-60, I wouldn't go above the FC level of 40 since that should be enough to zap even this hearty algae, and it sounds like it is. At this point, just wait this stuff out keeping the FC at the high level. Don't worry about adding any more acid at this point -- your dropping TA could mean that your pH isn't really as high as you think (due to high chlorine and extra thiosulfate drops) and when the chlorine level drops back down (after you've conquered your algae problem), the pH will drop anyway. Just add the baking soda to bring up the TA again (I wonder if the algae is consuming the carbonate???).

And hang in there -- you are on the right track! Oh yes, with this much junk you are killing in your pool, you will probably have a lot to vacuum out and/or to clean out of your filter. You might check your pressure to make sure you haven't caked your filter with this stuff.

As for algaecide, some people have reported success using 60% polyquat algaecide, but this is best done BEFORE the algae starts -- as a preventative -- so would be something you would add before August each season since that is when people first start reporting this hard-to-kill yellow/mustard algae (which sounds like what you might have). Perhaps keeping higher chlorine levels would also prevent this stuff, but we don't know enough yet of how high that would have to be (i.e. is the high end of Ben's chart good enough to prevent this stuff???).

Richard

[dawndenise]

Richard,

Thanks for the encouragement. Once I decided to go with the theory that this was algae, I really thought I'd be cleared up by now. Dump in a bunch of bleach, filter on 24/7 and wait 24-48 hours and - presto! - a clear pool, right?

The odd thing is that I truly thought my CL levels were on the high side prior to this. I guess a lot of organics can overwhelm even a relatively high CL.

Also had another thought on how this happened - a hose. We used a couple of hoses strung together to siphon out our pool during construction when it was pretty grungy and we were hosts to a number of toads (we relocated them prior to draining). We were also concerned about mosquitos breeding in the standing water. I don't remember exactly which hose was used for discharge of the grungy water, but I know certain hoses we use a lot, were not. Normally, those known-clean hoses are the hoses I use to top off the pool.

Just 3-4 days prior to the first white-ish haze, we cleaned the filter and I had to connect 2 hoses to reach the area. If the second hose I connected happened to be a previous discharge hose, well, then I could have introduced heaven-only-knows-what directly into my filter . That combined with the organic overload might have triggered this whole thing.

I'll be trashing all suspect hoses.

[dawndenise]

Final update: Pool cleared and came back to its nice color on Day 9, although a bit of whitish haze around the drain persisted. Kept CL levels up for another day and by Day 11 began to let the pool come down to its normal levels.

This morning's readings (would be Day 13, if still counting) are FC 15.5, CC 0, pH 7.5+, TA 70. SWG at 35%, salt level 4000-4100 (due to mega bleach additions), pump back on 10hrs.

Things learned:

1.) Shock the pool to whatever level it takes at the first sign something is not quite right with your pool - trust your instincts.

2.) Keep a good supply of testing reagents on hand. Testing FC at 30-48 3x/day can use up a whole lot of drops!!!

3.) Don't use scummy hoses to top off your pool or clean your cartridge filter.

4.) Keep one shock level of bleach, or cal hypo, or whatever, on hand so you can take action on a problem immediately.

5.) Seriously think about adding some polyquat 60 in August or early September.

The PS234S was indispensible! Can't even imagine how I could have managed this outbreak with the shot glass method (nothing against the method, but doing a reading with 1 part pool water and 5-9 parts distilled water would have been just too inaccurate).

Thank you Richard for your advice and encouragement. Thanks to the others who posted on other threads/forums where I posted other questions before I knew what I was dealing with.

Missed probably 1-2 days of swimming during this, as the temps have been cooler. Pool was at 68 degrees this AM but we have 3 days forecasted to be in the 90's with overnight lows in the 60's, so may be able to squeeze in a few more dips and laps. Should help to lower that CL reading just a bit, too.

[chem geek]

Sandy,

That's great news and I'm so glad that you conquered this algae. Your tips of what you learned are also excellent.

Another alternative or even in addition to using the Polyquat 60 in August each summer as a preventative for algae would be to have 50 ppm Borates (from Borax) in your pool (at all times). We don't know yet if the Borates will prevent this particular hard-to-kill algae, but I suspect that it will be at least as good as Polyquat 60 for preventing algae plus has additional benefits of greater pH buffering (stability) and lower chlorine consumption. Apparently, Evan's got me "hooked on Borax" and I plan to add both salt (1000 ppm just for the "feel") and Borax (50 ppm) to my pool starting next spring.

Richard

[dawndenise]

Haven't yet studied the threads on borates but plan to do so. Anything to not have this happen again will get serious study from me!