Sand filter 30psi...Water not circulating

lukeaz1

Member
Feb 26, 2018
6
Phoenix AZ
Hello Pool People,

I have an old sand filter. I backwashed it 2 days ago, and it was running fine thereafter for a few hours.

I woke up yesterday and the pool was running but very loudly - so I checked it out and noticed the psi on the sand filter was at 30. So I turned off the pool right away. I noticed that the vacuum had no suction, and there was practically no water coming out of the return jets in the pool.

I tried backwashing again, and though it seemed like a ton of air came out of the hose initially, I was able to backwash and the psi at that point was around 20.

I turned the pool on again and it shot up to 30 again. I turned off the pool and opened the sand filter, and it was almost full of water.

I don't know what to do at this point. The skimmer basket is empty. Here are some recent water test results:

FCL: 9.83
TCL: 9.29
BR: 18.6
PH: 7.8
ALK: 72
CH: 504

I have a diving pool I don't know the gallons but its pretty big. Any help would be MUCH appreciated.

Thanks,

Luke
 

lukeaz1

Member
Feb 26, 2018
6
Phoenix AZ
Thanks, it's nice to be here... the water looks excellent, clear. I backwash it for a few minutes I guess. I just wait until the water coming out of the hose is clear. It usually starts out a little murky.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
Hello Pool People,

I have an old sand filter. I backwashed it 2 days ago, and it was running fine thereafter for a few hours.

I woke up yesterday and the pool was running but very loudly - so I checked it out and noticed the psi on the sand filter was at 30. So I turned off the pool right away. I noticed that the vacuum had no suction, and there was practically no water coming out of the return jets in the pool.

I tried backwashing again, and though it seemed like a ton of air came out of the hose initially, I was able to backwash and the psi at that point was around 20.

I turned the pool on again and it shot up to 30 again. I turned off the pool and opened the sand filter, and it was almost full of water.

I don't know what to do at this point. The skimmer basket is empty. Here are some recent water test results:

FCL: 9.83
TCL: 9.29
BR: 18.6
PH: 7.8
ALK: 72
CH: 504

I have a diving pool I don't know the gallons but its pretty big. Any help would be MUCH appreciated.

Thanks,

Luke
Welcome to the forum.

Those test results are a bit confusing/misleading.

TC cannot be lower than FC, as TC is the sum of FC + CC (FC+CC=TC). CC would never be a negative value.

Both chlorine & bromine are listed, is this a chlorine pool or a bromine pool?

What is your CYA level? Your proper FC level is a function of your CYA level. Without knowing CYA levels it is impossible to know if your FC levels are adequate (unless of course this is a bromine pool).

Now, with all that said, I assume these are pool store test results?

We don’t give much credence to pool store testing, it has proven to be inaccurate and unreliable most of the time (eg the FC/TC levels reported).

What test kit are you using for your daily testing?

How do you normally sanitize the pool?
 

lukeaz1

Member
Feb 26, 2018
6
Phoenix AZ
I just bought a test kit... it was the lamotte color q pro. I may have not tested the water right, I can try again this afternoon and update the results. Do you believe the root of my high psi issue stems from the water chemistry?

Normally I just keep 2 or 3 chlorine tabs in the floater, and I dump in about a scoop (which i think is somewhere around a cup maybe?) of granulated chlorine every week or so. I admit I don't really know what I'm doing.
 

domct203

Bronze Supporter
LifeTime Supporter
TFP Guide
Jun 3, 2015
3,959
CT
No worries, if you are willing to learn, we are willing to teach.

I’m not too familiar with the Color Q, does it require regular calibration?

When you re-test, be sure to get a CYA level.

As mentioned, do you have algae. Does ‘fine dirt’ collect on the floor, the kind that poofs away when you try to sweep or vacuum?

How does the water look? Is it cloudy at all?

Yes, inadequate sanitizer level can let algae start to grow, which will tends to clog up filter media quickly. Algae is always a chemical balance issue, not a filter issue though.
 

lukeaz1

Member
Feb 26, 2018
6
Phoenix AZ
Water is crystal clear. No sentiment or algae. I'm going to test the water again and will find the name of the filter and pump. When i did the initial test, it said the CYA was 'high'.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,791
Laughlin, NV
ColorQ will only test FC to 10 ppm. So not usable for a SLAM.

It states CYA up to 125. I think High means over that -- which would be likely if a pool in Phoenix has uses solid chlorine (trichlor pucks, is the powder dichlor or cal-hypo?).

Algae can be present and you will not be able to see it. But your instant increase in pressure may be that the sand is compromised by past use of pool store potions. Have you inspected the sand? A Deep Clean may be necessary - read Deep Cleaning a Sand Filter
 

cfherrman

TFP Guide
May 10, 2017
2,403
Hays, Kansas
Turn everything off and pull your pressure gauge out and see if it still reads 30 psi. If your pump is pumping it will have pressure, if your skimmer is empty and your not pumping there will be no pressure.
 

lukeaz1

Member
Feb 26, 2018
6
Phoenix AZ
Thanks everybody.. I did the 'deep clean' and it seemed to work. The gauge stays at about 5 when its off. So when I take off that 5 the gauge now reads about 18 when running. Thanks for the help!