Zero Pressure in Filter Chamber

[JPhresh]

About two months ago I disassembled the filter chamber on my system so I could clean the filters. Before I did the cleaning, the pressure gauge on the top of the chamber was showing about 15 psi. Once I opened it, I discovered that the previous owner had not cleaned it in quite a while -- there was about two to three inches of sediment in the bottom and the filters were completely caked in fine material. After I got everything cleaned and reassembled, I immediately noticed that: (1) the water flow was vastly improved, (2) the pump was running more quietly and (3) the pressure in the vessel was down to near zero.

Of course I was very happy with this initially, but am now starting to get concerned that I should be seeing some pressure in the filter chamber. It's still basically at zero. The water in my pool is nice and clear, but it's also 45 degrees, so any microbes that might cloud up the water are going to have a tough time getting a foothold. (I'm also religious about scrubbing and maintaining chemistry balance, which I'm sure doesn't hurt.)

So, I guess my question is this: is it possible that the filter is acting effectively even if the pressure in the filter vessel is zero?

Thanks in Advance,
-J Phresh

 

[kimkats]

J,

I see you have your filter listed as ? sqft filter (Durex Triton C&C Plus). When I did a search on it I could not tell what KIND of filter it is-sand, cartridge, DE.

That would be helpful with your question.

I do want to ask if your gauge goes down to 0 when the pump is off?

Kim

 

[Jimrahbe]

J,

In the perfect world, filters would have no resistance to water flowing through them and the pressure would read zero. Unfortunately, most filters have some resistance to water flow, even when clean, so there is some pressure. For a lot of DE filters the clean pressure is about 10 PSI and it increases to 20 or so as the filters get dirty. The exact pressure depends a lot on pump speed and how much water you are trying to move through the filter.

In my case, when I run my pump at about 1,000 RPM, my pressure is only 2 or 3 PSI.

So, what type of pump do you have? A single speed, a 2-speed, or a variable speed?

1. If you have a single speed pump and only get 2 PSI, then I would assume your gage is plugged up or not working.
2. If you have a 2-speed or VS pump, I would assume the pump is on low speed.

Jim R.

 

[Divin Dave]

There will not necessarily be a discernible pressure reading on your gauge.
1- because if you have one of those cheap gauges on the filter, they are not terribly accurate. There probably is some pressure, just not enough for one of the OEM cheap gauges to register it.

2. The answer as to how much pressure you should have will depend on how much flow is going through the filter and how large the filter is.

If you dont have high flow, and you have a large capacity filter, then it is entirely possible for the pressure to read near 0.
And yes, its filtering fine if pressure is that low. The lower the pressure is actually a good thing.

One thing to check however, is to make sure you dont have the multiport valve (if you have one), set to "recirculate" instead of "filter".

Mine reads only 1.5 psi during normal operation. I have a 420 sq ft cartridge filter and I am "guessing" my flow rate is about 30=35 GPM.
Im also using one of the nice gauges which tftestkits.net sells and its very easy to see exactly how much pressure is present.

 

[JPhresh]

Thanks for all the responses! First off, here is a photo of my filter setup:



The filter uses cartridges. The tag on it lists four different models, so I don't know which one it is... Hence the question mark regarding the square feet. It could be between 240 and 560 sf according to the tag. My pump is a single speed. The gauge goes down to zero when the pump is off, and come up just a little when the pump is on. As for the valves, I did not change anything when I cleaned the filter, so I should not be bypassing it.

So it sounds like it's possible that I could see a dramatic drop in pressure following cleaning, and it's equally possible the pressure gauge is just shot. Are there other possibilities? Perhaps I put the cartridges back improperly, or they were compromised by the cleaning process?

 

[Divin Dave]

That is a Pentair, Clean and Clear Filter. Its a top of the line filter. (Im guessing Pentair bought Durex, or Durex was a division of Pentair, ..but either way, its a Pentair filter).

Looks like a big one too. Hard to tell what size though.

EDIT: I have a CandC Plus 420. My filter height is between 42 and 43 inches from Bottom, to the top of the filter where the gauges screws into it. And the diameter of mine is 18 - 19 (as near as I can measure it).

EDIT 2: Your filter might be working fine. To add to that however, the head loss of the system will effect this as well. With a 2 HP pump and you didnt have a ton of head loss, I might expect the pressure to be a little bit higher. Make sure skimmer(s) are clean and pump basket clean and that you dont have any debris blocking the flow, then see what it is.



http://www.pentairpool.com/pdfs/CleanandClearPlusOM.pdf