Filter pressure gauge never changes - always 18 psi

handyharry

Member
Jul 23, 2019
14
Bourbonnais Illinois
I am new to this pool stuff after purchasing a house that has one. I replaced the old cartridge filter with a new Hayward sand system and it was suggested that I use Ruby Sand as the filter media. The pool was filthy with debris and algae which I have now conquered thanks to this site. SLAM!! The pool place totally failed me!! With all the stuff being filtered the pressure gauge has never moved from 18 psi even when backwashing was needed and return pressure low. I have talked to the Ruby Sand people, Waterway, and other pool places, but nobody has a clue about why this is happening. I have tried a new gauge which registered the same 18 psi as the original from Waterway so I ruled out the gauge, but Waterway is still sending me another one. I don't expect the gauge to change things. Every person in the business says I should not need to backwash unless the pressure rises 8 - 10 psi. Has anybody here experienced this kind of problem or heard of it so I have a clue as to what is going on to cause this??
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,020
Bedford, TX
Harry,

Have you backwashed since you cleaned all the gunk out of your pool?

What "magic" pool store chemicals did you add.. PhosFree, Clarifier, or Algaecide??????

Thanks,

Jim R.
 

Pool_Medic

In The Industry
Apr 1, 2018
965
Bangor Maine
It’s probable the gauge is broke, check the return flow, if it’s noticeably lower a back wash is necessary. You should be seeing a rise after an outbreak.
 

Islandman1960

In The Industry
Aug 12, 2019
1
Padre Island, Texas
I have experienced it. If it isn't a broken gauge, your return eye balls in the pool are probably causing more back pressure than your filter. If they are, your gauge will always read the same even if you remove the cartridge to test it. In my years in the pool business, I've seen this situation few times.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,020
Bedford, TX
I have experienced it. If it isn't a broken gauge, your return eye balls in the pool are probably causing more back pressure than your filter. If they are, your gauge will always read the same even if you remove the cartridge to test it. In my years in the pool business, I've seen this situation few times.
That quote defies logic.. The filter gauge basically measures the amount of effort takes to force water through the filter and back to the pool.. It is a series situation.. The resistance of all the items add together.. While the size of the eyeballs effects the total pressure, it can't make the other items, such as the resistance of the filter, just disappear..

Jim R.
 

handyharry

Member
Jul 23, 2019
14
Bourbonnais Illinois
Okay guys. Thanks. So to clarify all your responses - The gauge is not broken it drops to zero when off and a second gauge confirmed the pressure level. I have backwashed numerous times using the feel of the return pressure as a guide for whether it is needed. That's my ONLY method of possibly knowing when to do it. I agree with the return eyeballs making no sense as a cause. The only chemicals added after the SLAM is the formula for the Oxygen Pools hydrogen peroxide sterilization system and a little clarifier. Waterway isn't familiar with the Ruby Sand from Zeo, so they don't know if the smaller amount of "sand" (Ruby isn't sand) makes a difference. I keep feeling that there is a problem with the filter or filter media or a combination of the two not working properly. Can the filter have some kind of mechanical issue that would create this situation? I can't seem to escape the filter line of thinking as the cause.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,020
Bedford, TX
Harry,

I can't think of anything that would make a filter stay at one PSI reading.. Unless your filter is not picking up anything or the filter has a plumbing issue and the pool water is basically bypassing the filter.

I know nothing about Ruby sand, as regular sand works very well and we don't recommend anything else.. We have found over time, that sand substitutes have never lived up to the hype.

Thanks,

Jim R.
 

Bama Rambler

Mod Squad
TFP Expert
Bronze Supporter
LifeTime Supporter
Jun 22, 2009
23,535
SouthWest Alabama
Can you post a picture of your equipment and plumbing?
Can you tell us what size each piece of equipment is (pump model & hp, filter size, etc.)?
Can you tell us what size and how many eyeballs you have?
 
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TO116

Member
Jun 30, 2019
15
New Jersey
If the pressure at the returns decreases that means the water is passing through the filter and it is functioning.

The return eyeball theory makes sense to me, but I don't actually know the intricacies of pressure systems. If all of the sand was removed from the filter and the pressure to push the water through only the plumbing was say 15psi, thats obviously what the gauge would read. Now if you added sand to the filter and for arguments sake say it would take 5psi to push water through the sand with no plumbing afterwards (ie. on the rinse setting) Would the gauge read 15psi? or 20psi?

What I would do is just remove the eyeballs and see if the pressure changes, since it takes about 30 seconds. You could also check the pressure readings on the rinse setting as that would bypass the return plumbing.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
14,020
Bedford, TX
TO,

The size of the eyeballs has a direct impact on filter pressure.. Reducing the size, increases the pressure and increasing the size, decreases the pressure. But, the filter pressure is a total of anything in the water return path... It would be impossible for the eyeball size to make it so that a dirty filter would not increase the pressure.. In your example the pressure would read 20 psi... and as the filter got dirty the pressure would increase above 20...

Thanks,

Jim R.
 

handyharry

Member
Jul 23, 2019
14
Bourbonnais Illinois
In light of the fact that return pressure does change when dirty and again after backwash then the filter is working (I had not considered that angle). So a pressure change should show on the gauge, but somehow it doesn't. We had a 1 - 2 inch rain last night so I pumped to waste the excess water and observed that the pressure gauge read lower than normal during filtration, and that makes sense. It also makes me still believe that the gauge does work, so the mystery continues.
Thanks for all your thoughts.
Harry