keep getting algae on the bottom and cloudy water every weekend

[mikemedic]

I use the BBB method last year very successfully. My CYA was at 90 and Alternated 1-.75 bleach then 2-.75 bleach every other day. End result, clear water.
Now this year with backwashing weekly and adding water weekly I have algae forming on the walls every few days and it's frustrating.

Here are some averages for this year
CYA is at 40-just tested today
FC has been avg. 6 ppm has fell down to 3 ppm by eve a few times.
alk avg. 70-90
ph has been little higher 7.4- 7.8

I think I got better results last year with higher cya. My avg. FC loss a day is 4.36 thanks to my xcel spread sheet.

Ok any one want to give me suggestions, I am thinking about using some trichlor pucks to lower my ph and add a more constant FC.

I seem to be losing quite a bit more Fc this year. I can get FC to shock levels
and clear up in a few days crystal clear but by end of week it's cloudy and has some algae on the bottom

Thanks
Mike

[chem geek]

Mike,

You may have had less FC loss at the higher CYA. We're still sorting that out but it does seem to be the case. As for the algae you have, it sounds like yellow/mustard algae because at a CYA level of 40 it takes a minimum of 6 ppm FC to keep away and your FC sometimes dips below that. Yellow/mustard algae is heartier than green algae so takes more chlorine to keep away and more to shock. To shock it at 40 ppm CYA you need to first lower the pH to 7.2 (with acid) and then add chlorine to get to and maintain 24 ppm FC holding it even a couple of days with no loss overnight.

You are actually in better shape this year with your lower CYA because if you got this algae with your higher CYA last year it would take extraordinary amounts of chlorine to kill it (at 90 ppm you have to maintain 13.5 ppm FC to keep the algae away and 52 ppm FC to shock it!). You should wash your swimsuits in hot soapy water to prevent reintroduction of this algae though it may be getting blown in which obviously there's not much you can do about except keep a higher FC level. You can read other threads on this forum about yellow/mustard algae. I'm sorry you got it.

Richard

[mikemedic]

Damn Mustard Algae!
The water had a slight green tinge again, but there is greenish yellowish tinge on the bottom. How can I tell whether its green or mustard or do I care.
I still think my pool is better at higher cya.

I brushed and fc was about 10 tonight so jacked it up to 20 and brushed again.

[topless]

I'm no chemist, so I won't give you any advice along those lines.
But, having fought mustard algae for the last 4 years, I will offer some additional advice.
I finally stopped it last year, after I soaked or washed all the toys, floats, and pool tools with very highly chlorinated water. Including my Polaris and it's hoses.
I decided that I was re-introducing the algae with something after I killed it off in the pool.

[chem geek]

Good advice from topless. As for how to distinguish between green algae and yellow/mustard algae, it's usually easy because green algae is usually free-floating and gives water a cloudy to green color. Yellow/mustard algae looks more like powder or dust and is on pool surfaces including sticking to walls and usually starts growing on the shady side of the pool. Unfortunately, pollen and dirt are often mistaken for yellow/mustard algae, but the former do not continue to grow if put into a partially covered bucket. Algae tends to feel slimy while pollen and dirt usually don't (though pollen can feel, well, strange). A definitive test is to look at some of it under a microscope.

The reason I said you probably have yellow/mustard algae is that you said it was forming on the walls. That usually doesn't happen with pollen/dirt nor with green algae.

Richard

[mikemedic]

Ok, thats what I am treating as. I brushed the bottom and notice "clouds" of dust. I have noticed something floating on top of the pool for the last few weeks, the pool is near a gravel private road and thought that was pollen
I have the FC at 24 right now and the ph is about 7.2 with the help of some pucks and supplementing with bleach. CYA was 40 yesterday
I just brushed and even though the shallow end didnt fell slimy when I went in I brushed I noticed a murky dusty bottom as I brushed then clouded up the water. How do I know when the chlorine has killed this monster? My FC will hold thru the night, should I keep above 20 Fc for how many days?