Is there still sand in my filter?

dford8583

Active member
Nov 30, 2019
37
Mobile, Alabama
I bought a house with a pool and have been learning and doing my own pool care. I have a sta-rite crystal flow (300 lb.) sand filter. I had a new pressure gauge added when the pool tech was giving me a pool school. He showed me how to backwash the filter and we read the gauge afterwards when the pump was running. After backwashing, the gauge was ready at 10 psig. That was 3 weeks ago. When I read the gauge it is still at 10 psig.
-I am wondering if this is normal for there not to be any change in pressure across the filter after this long?
- Also, when I look in the water at night, there are particles floating everywhere. I have my chemistry balanced and have just done an 85% water exchange over the weekend. I know that a sand filter doesn’t filter as fine as cartridge or de filters. But should I still see little particles floating everywhere?
-could i need to replace some sand? how can I tell? The filter is accessible due to threaded fittings.

thanks for any input! Checking off various things as I go and as I learn more! Loving the site and pool math app
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,216
Spring Valley, NY
As we can't know what's floating in the water but you say just bought house. We will need pictures of the equipment pad and pool to see what you have so we can help you out. There may not be enough sand in the filter or the wrong type of sand if it was changed by someone before you got there which may be what you're seeing. 10 psi is good and that's if the water doesn't have much to filter out but as you say stuff is floating around which doesn't seem correct with a non rising psi.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
16,369
Northern NJ

Sand filters down to 30 microns; cartridge filters down to 10 microns; DE filters down to 3 microns.

Looking for particles in your water at night is not a good way to evaluate filter performance.

A filter can go a whole season without needing cleaning. In 3 weeks I would not expect filter pressure to rise in a clean algae free pool.

I think your filter is working fine.

 
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Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
23,874
SouthWest Alabama
If you want to clear up some of those particles you see in the light at night, you can add a couple of cups of DE (Diatomaceous Earth) to the filter and while it won't get them all it'll get some of them.

If you want to try it and you don't want to buy a whole box of DE, I'll be in Mobile the 13th and I have plenty I'd be glad to throw on the back of the truck that you can have. PM me if you're interested.
 
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dford8583

Active member
Nov 30, 2019
37
Mobile, Alabama
If you want to clear up some of those particles you see in the light at night, you can add a couple of cups of DE (Diatomaceous Earth) to the filter and while it won't get them all it'll get some of them.

If you want to try it and you don't want to buy a whole box of DE, I'll be in Mobile the 13th and I have plenty I'd be glad to throw on the back of the truck that you can have. PM me if you're interested.
Thanks Bama! I appreciate the offer. I’ll think about it.
 

dford8583

Active member
Nov 30, 2019
37
Mobile, Alabama
I have noticed that there are lots of particles and there is what looks like a sheen when I look at the pool with the pool light on. Looks great during the day but at night it kinda grosses me out. Is this something the filter should be taking care of? I understand the sand filter isn’t the best filter in terms of particle size. I just thought it would be better.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
1,216
Spring Valley, NY
With knowing your clean filter pressure add de a few cups at a time till you see a 1 psi rise and stop. That amount is your known figure you'll work with everytime you add de after a good backwash. Let the sand filter do its thing. Day by day it'll eliminate all that stuff but be prepared for major psi rise the first few times as it catches all that in the filter and restricts. Make sure your available to backwash and not like I'll be back in 8 hours otherwise it's risky with the the pump.