Help! New DE filter requires backwash multiple/day

kez1312

New member
Jun 2, 2023
1
Northern VA
Pool Size
35000
Surface
Plaster
Chlorine
Liquid Chlorine
Background: bought house last year before summer with ~35k gal pool unopened. Tried to open and found few leaks from improper winterization so didn't 'open' until July. Original installation ~2005, everything looks original to then except pump replaced 2016. Sand filter old but pool guy said should still work but didn't, so we replaced sand with zeolite (around Aug) and hoped for the best. LSS, zeolite didn't seem to work great either, pool never really got super clean last year and we closed it around Sept.

This year we decided to stop playing with the old filter and upgraded to Pentair DE 60sqft (little oversized for the pool). Installed on 5/27 around 5pm, added 6lb DE and ran overnight. In AM (~8ish) pressure was 30 (starts at ~19/20), so backwash and add 3lb more. By 1pm ish needed to backwash again, so same procedure. By 8pm again 30, backwash, 3lb more. On to the next am, ~32 at 8am; decided to open and clean out filter. Then added 6lb. Lasted a little longer, to about 4pm to get to 30, backwash +3lb. Same 32 the next am so backwash and then let it sit for a few hours before turning on again. In between having the filter run I alternate letting the robot run (it seems to make the pressure higher if I filter at same time as run robot (polaris 280) so I'm alternating between recyling water+robot and just filter. This has basically been the procedure since then - starts at 20, gets to 30 within 2-4 hours. At this point I've backwashed/cleaned so many times I've already ran through an entire bag and 1/2 (24lbs each) of DE. The pool was dirty (still a little) but getting steadily better, but this seems excessive. What am I doing wrong? How to improve this process?

Question 2: We are now in chlorine lock. Pool store suggestion was either 1)super chlorinate (18lbs shock) and hope that clears it, or 2)let the current stuff burnoff and add more water in the meantime to help it go faster. Thoughts on this?

Question 3: (Tied into question2): Can we run DE filter for 1day only WITHOUT DE? My thought was this might help clear out the bigger stuff (we would backwash like every 1-2 hours) while also meeting the goal of adding more water to help get rid of some of the existing chlorine lock problem. and then get back to starting over with the DE as normal and maybe by then it's at a normal operating level? Will this hurt my brand new filter if I do this?
 
Welcome to TFP! :wave: I can sum-up just about everything in your post with two key phrases: Proper water testing & algae control.

You have been jumping through hoops (also some bad advice) to change filtration methods when what you are describing with high pressure is most likely due to algae. A heavy organic load clogs a filter very fast, and I'm sorry to say, but DE filters clog up the fastest, so don't expect that to change anytime soon.

Chlorine lock is a false pool store term that basically means your CYA level is too high and the FC level cannot keep up with it. See our FC/CYA Levels to understand the correlation of the two.

Do NOT run your DE filter without DE. If you have a MPV, you can run it on recirculate. If you have a slide backwash valve, you're stuck.

Priority #1 is a proper test kit. Either a TF-100 or Taylor K-2006C. You need one of those. Post a full set of test numbers and we can help you through this. But the test kit is step #1.

Also see our Pool Care Basics page for lots of great info. We'll be here to help.
 
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