white fine residue on floor of pool

Hi,

I have a dilemna with a pool that I have built of which I haven't seen to this extent before. Maybe other pool owners have dealt with this.

Pool : 20 x 40 vinyl liner inground . salt system. Hayward s244s sand filter with zeobrite media.

Problem: the pool floor especially in front of the jets is covered with extremely fine white dust. At first we thought it might be a broken lateral but the dust really wasn't the consistency of the zeobrite that you would expect to see. We vacuumed it off and it came back. We removed the zeobrite media in the hayward sand filter and checked the filter laterals and all were intact. I've built hundreds of pools exactly like this with this never happening to this extent before. Can anyone help with this puzzle?

By the way, even though I've built pools for decades, I've been looking to Ben and this site for answers since I found it over 10 years ago and have to say it is the best place to go online for advice.

Do you have a K2006 test kit? (If not, get one) Note that the HTH kit tests TOTAL hardness, rather than CALCIUM hardness.

Check the calcium, pH and alkalinity levels. My guess is, you may be seeing calcium attaching to the SWCG plates and then flaking off when the unit reverses polarity.


+ Here are links to the kits we recommend:

HTH 6-Way Test Kit @ Walmart
Taylor K2006A (3/4 oz bottles) @ Amazon
Taylor K2006C (2 oz bottles) @ Amazon

Thanks for the quick reply Pooldoc. I figured it had something to do with the swg but the reverse polarity self-cleaning feature flaking is a new twist I didn't think of. Thank you for the info .. I will get the k2006. I've always used my distributor supplied brand 4way and then I'll adjust the CA and TA (PH is running about 7.8 after muriatic acid seasonal adjustment; which has been a little high but okay). Next - I'm going to turn the salt gen off for a few weeks and go straight chlorine and vacuum the dust up to waste and see what happens. if it goes away, I'll turn the swg back on.

Welcome to The Forum!! (I love seeing pool dudes come here to learn their job better)

I had an issue with one of my pools last year that sounds kind of similar - the pool was cloudy, white/ bluish, and the chems were ~ perfect, the stuff wouldn't go away. There had been some construction done in the lot adjacent to the pool over the winter. I added DE to the sand filters and the problem fully cleared itself in a couple days.

I don't know if the 'DE in a sand filter' trick works for zeo, but, given that the debris is in front of the returns, you should look into the cause being something too fine for the filter to catch. If DE is contraindicated for zeo, you might have to use a floc.

Have a good and prosperous season!