Slightly cloudy with brown residue at the bottom

[proximo]

Thank you, thank you PoolDoc and Watermom! I really appreciate your responses.

Last fall I did the Borax treatment you recommended here. Although the strip test I have isn't terribly accurate I think it's around 50ppm. I will keep raising it though as we may have lost some due to water changes.

I've kept the chlorine levels around 20ppm and it's crystal clear this morning! Just have a ton to vacuum out now off the floor. Would you keep the pool at shock values longer? If so how much longer to totally kill the mustard algae?

I may switch to liquid bleach as I dont want to raise my CYA anymore. I'm just afraid I'll forget a dose!

[nottapooltech]

How is your pool now? I am having basically the same problem. I am curious if you still have a lot of sediment/dead algae on the bottom?

[proximo]

I shocked the heck out of the water for about 5 days. I kept the chlorine levels at 20+ during that time. So far the water has remained clear. We had to keep vacuuming the sediment out to waste. Takes several days because it's so fine - like a powder. Even as you vacuum you stir it up and it blows around in the water. I think it just patience and persistence to shock it long enough to kill it all and then vacuum it all out. I'm not 100% sure I've killed it all but I guess time will tell. I bought a pool vacuum with a fine filter to help with the process.

[PoolDoc]

Sounds like you are on track.

Successfully vacuuming fine dust like that requires a well-functioning filter, a good vac head, and patience.

If you are having trouble with the dust blowing through the filter, adding DE to the filter via the skimmer, just prior to vacuuming, should solve that problem.

A roller vac will allow you to vac up the dust, without stirring it up the way a brush vac will do. The Rainbow (now, Pentair) ProVac has been the model we've always used ourselves, and have placed at the large commercial pools I have serviced. There are multiple sizes; do NOT get the larger models unless you have EXTREMELY strong suction and flow at your skimmer. We currently use the 22" model -- but we attach it to a dedicated 1 HP vac pump. Here's the model you want:

Pentair R201276 214 14" Pro Vac Series Vacuum Head @ Amazon

Regardless of vac head, when vacuuming fine dust you must move slowly. I've only rarely been able to get teen aged lifeguards to do that without standing over them, constantly saying, "Slow down, you are stirring up the dust. Easy. Focus on smooth slow movements." etc, ad nauseum. But, that's what it takes. And, if you have a good vacuum head, a well functioning filter, and vacuum correctly, you can do a complete pool surprisingly quickly. We can do a 45 x 75 pool that way in 2 hours, so even allowing for the smaller 14" head, you should be able to complete an entire residential pool in less than an hour!