CYA cause increase in Sand Filter Pressure

[John85]

Hello,
I'm opening up my pool (all new water), shocked and cleaned for two days, using 12.5% Cl and a little bit of DE two help pull stuff out. Backwashed twice (flush DE/dead stuff). I started adding my CYA (in socks in front of returns) this morning so I can start to SLAM properly. The socks are 1/2 - 2/3 empty (will bring level to 24 or so when all incorporated). My gauge on the sand filter is reading almost 25 (usually 15-17).

Does/can CYA cause an initial spike in pressure that will go down naturally?
Is it possible (I suppose) that there's still some DE in the filter (I backwashed until clear, not 30 seconds)?
Should I worry about leaving my filter at that kind of pressure for a few days so I don't flush all of my CYA?

Thanks!

 

[samt]

I never had that happen when I added CYA the same way as you did. Now DE is another story, it takes just a very little bit of that, 1/3 cup and if the pollen is high, I have to backwash in about 3 hrs cause my preasure builds so much.

Is it possible you still have some DE in there and as the pollen gets worse the remaining DE is trapping that junk and raising your pressure. It takes a number of back washes before you get all that DE out.

I do like that DE, it works like a charm with my sand filter. I only use it in the spring, it works good.

I don't like letting my pump run when I not there to watch it when using DE. I think it could do some damage that I'm not going to chance.

 

[Richard320]

I never had that happen when I added CYA the same way as you did. Now DE is another story, it takes just a very little bit of that, 1/3 cup and if the pollen is high, I have to backwash in about 3 hrs cause my preasure builds so much.

Is it possible you still have some DE in there and as the pollen gets worse the remaining DE is trapping that junk and raising your pressure. It takes a number of back washes before you get all that DE out.

I do like that DE, it works like a charm with my sand filter. I only use it in the spring, it works good.

I don't like letting my pump run when I not there to watch it when using DE. I think it could do some damage that I'm not going to chance.

 

[John85]

Well I certainly backwashed enough to get the DE all out, but my pressure climbed from 16 back to 25 (over the course of 18 hours or so). I think it could be dead algae/dirt and pollen, but have kept adding the stabilizer (8 lbs dissolved in socks in about 30 hours).

Does it really take 3-4 days for the stabilizer to show up in a test? I think I ought to backwash but don't want flush even more CYA if I can help it.

 

[samt]

Perfect timing.?

 

[John85]

I went ahead and did a CYA test. 30-40 ppm (if it all absorbed it would have been 35 or so, all of the water was new). My only hesitation is that My reading is high because the socks are in the pool and I think a lot of the CYA may not have made it through the system yet (probably over thinking it). I think I'm at the point of just sucking it up and eating the loss (buying more CYA if I need) and backwashing because I need to. Thanks for the input all.

 

[Richard320]

I went ahead and did a CYA test. 30-40 ppm (if it all absorbed it would have been 35 or so, all of the water was new). My only hesitation is that My reading is high because the socks are in the pool and I think a lot of the CYA may not have made it through the system yet (probably over thinking it). I think I'm at the point of just sucking it up and eating the loss (buying more CYA if I need) and backwashing because I need to. Thanks for the input all.

Backwash whenever you need. Any undissolved CYA is in the sock. That's why we recommend that method. The CYA bottles usually tell you to pour it down the skimmer, and it ends up in the filter while it dissolves. And if you need to backwash before it's all dissolved, oh, well, too bad.

 

[John85]

Ok cool, yeah it makes sense it would be in the sock, I guess, I just saw that numbers in test results can keep climbing for several days after the add. And really we're talking more stabilizer at $17 a bottle v. significantly more for a new pump. So I'll backwash.