Used the wrong DE

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scader

scader

Well-known member
Jul 3, 2016
54
Overland Park, KS
I had to open the pool late due to repairs to plaster in the shallow end. There was a lot of organic material in the deep end that wasn't emptied, very green (and frog city). I used fair amount of algaecide before I learned that was a mistake. The pool is now full and i can finally vac to waste without having to dump the skimmer basket of debris. Pool is mostly blue, but cloudy. Even in normal years it's always cloudy when I open and only flock has helped. Now I'm wondering if flock is what damaged the plaster in the shallow end. I slamed the vinyl pool at our last house with much success, but same effort with the plaster pool at current house has not been as successful. I blame me, but it's odd given the process is simple.

I'm going to stop all my nonsense and get back to slamming, but the point of this post is to ask about DE. Very excited to use that vs flock, but the top google search result which linked to this site did not mention there was pool grade DE (see link below). I only found this out by looking at results further down within the forums. Might be something good to add to that blog page. Add DE to a Sand Filter

My question (actually got there) is what effect, if any, does 3 cups of food grade DE have to the pool? Is food grade just finer and pointless? I'm not worried about human consumption if it remains in the water at that dilution.
 
DE grade is indeed finer and depending on your filter can remain in the water, in suspension, for quite a while leaving it cloudy. If you have a sand filter it could take a while to finally get caught and removed. If you a DE filter it should get filtered.
 
Yeah, I added it before realizing it was different from pool DE. Found pool time pool DE at HD to add tonight.

The pool is mostly blue, just cloudy, so not sure if that is algae or just other organic material. Going to slam this evening.

Is it worth slamming if CYA is only 20? Still need to work on getting that up to 60 or so...
 
Update: I added 2 gal of liquid chlor last night and after 2hrs it settled at 21ppm (only need 12ppm according to calculator). At 7am this morning still at 21ppm. Interesting that it didn't go down overnight.

At 10am 17ppm; at noon 12ppm. I added half gal to keep it above 12, will check again this afternoon before I take final sample and add chlorine this evening.

The psi went up by 1 after a cup of pool DE. By this morning it was up another 4psi. How much do I let that ride before backwashing to start over? Is it more effective to keep it dirty as that collects more? What is max psi to safely allow?
 
scader said:
Interesting that it didn't go down overnight.
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That means oy passed the overnight chlorine loss test. That's great. :goodjob: Should be no active algae concerns and no need to maintain an elevated FC level. You can let it slowly fall back to the ideal range as noted on the FC/CYA Levels.

scader said:
How much do I let that ride before backwashing to start over? Is it more effective to keep it dirty as that collects more?
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They do filter a little better when dirty. The finer stuff gets trapped better. In general, we recommend backwashing when the psi increases by about 25% from the clean pressure. So you might try to gauge the pressure by that window so that you don't go too high.
 

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