Cloudy Dark Water

[trg808]

I have a 35,000 gal (yes, i'm certain of the size, everyone asks.) salt water pool that over the past two weeks has slowly gone from a little cloudy to very dark. I routinely put 4 capfuls of pool perfect + phos free in the skimmer weekly, and shock once a month or if the chlorine tests low. The weather has been very hot, 110+, for several weeks. It finally rained last night and has cooled off some today.

I went to the local pool store to get the water tested and the results were:
FAC 4
TAC 4
Ph 8/2
Total Alkalinity 120
CYA 45
Salinity 3,400

They didn't see anything wrong with the water except the Ph being slightly high, which is normal for this area. They suggested 1/2 gallon of muriatic acid (will add tomorrow). They said even though the chlorine is normal, I should add 1lb of shock to try to kill what ever is making it cloudy. And vacuum it. They didn't think it was algae because the sample was clear.

I have vacuumed it several days in a row and it always has a coat of something all over the bottom and sides again by morning. I have left the pump running constantly with 100% output for 3 days straight now and no improvement. I can not see the bottom of the deep end and the shallow end looks very cloudy. I just added the shock they suggested a few minutes ago and noticed what looked like flecks of dirt coating the top of the water. When i skmmed my hand across it, i could tell that it was little bugs. It looked like yeast does when you sprinkle it on water.

Any thoughts on what could be going on?

[PoolDoc]

Welcome to the forum!

To solve your problems, I think we'll need a little more info. So, here are some initial steps AND questions for you to answer:

#1 - Get your pH down to the 7.2 - 7.6 range, as you indicated you planned to do.
#2 - Buy 20 gallons of plain 6% household bleach (or 10 gallons of 10 - 12% liquid pool chlorine) and a cheap OTO/phenol red testkit.
#3 - Add 6 gallons of bleach tonight.
#4 - Stop using the pool perfect / phos-free, at least for now.
#5 - Start running your pump filter 24/7, if you aren't already doing so.
#6 - Continue with bleach doses at night to maintain DARK yellow OTO test readings the following morning.
#7 - Tell us what COLOR the water is -- "dark" gray? green? brown?
#8 - Take some pictures of the pool and your pool equipment and send them -- full size -- to poolforum.pics AT gmail DOT com so we can post them.
#9 - What color is the "coat" that's on the pool in the AM?
#10 - Are you adding any other chemicals, besides the ones you mentioned?

[trg808]

I'll get started on this. Thank you.

#5. On day 3 of 24/7 pump action
#7 very dark green
#8 brown

[PoolDoc]

Yup.

Do the chlorine as instructed -- repeat dose in AM if chlorine is below 5 ppm.

If you don't see significant color change 24 hours after the first dose, increase the dose to 10 gallons in the PM. However, if your pool is vinyl, drop back to 6 gallons after you have a color change AND are are holding "dark yellow" overnight.

AND . . . except for adjusting the pH, do NOT add other chemicals. By the way, check your pH levels in the evening BEFORE you add the PM chlorine dose. Very high chlorine changes the phenol red indicator, to another indicator "chlorophenol red" which is violet purple at pH levels above 6.8.

Ben

[PoolDoc]

Adding pictures . . .
(trying to work out a better way of handling them in 2012)
Green algae in pool




Algae dust on steps