DE filter pressure

[carlos31]

Is there a minimum pressure required for a DE filter?

I am running very low pressure with my Quad DE100. The filter gauge usually reads 0 - 3 psi. I know water is flowing because I see the check valve open and the flow meter indicating 35 to 45 gpm. However, is this a problem for the filter? I checked the manual but only a max pressure is provided (50psi), no minimum.

thanks,

carlos

 

[HarryH3]

That sounds quite low to me, but I have a 2.5 HP high head pump pushing water through a 60 sf DE filter. After a backwash and reload, mine runs at 13 psi. I suppose that with less pump pushing the water the pressure would be much lower.

 

[spishex]

Is there a minimum pressure required for a DE filter?

I am running very low pressure with my Quad DE100. The filter gauge usually reads 0 - 3 psi. I know water is flowing because I see the check valve open and the flow meter indicating 35 to 45 gpm. However, is this a problem for the filter? I checked the manual but only a max pressure is provided (50psi), no minimum.

thanks,

carlos

Do you know for sure that the gauge is working? If you have valves on the return side you could close them a bit to see if your pressure goes up.

There's no minimum working pressure except that you need enough water flow to turn the pool over. In fact, the slower you put water through the filter the better it performs and the longer your grids will last. That's one of the main selling points of your pump.

 

[stever]

I have seen low pressues with my Quad-100, but not that low. At 28 gpm (or so) it's at 12 psi. It never changes from that pressure - even when it needs cleaning -- you have to schedule your cleanings, as it does not indicate by raised pressure. The filtered goop seems to settle into the bottom of the tank.

Do you have large diameter short-sun pipes? I agree that this seems really, really low.

Steve

 

[carlos31]

Well my FC was 8 this morning with CC = 0 so the LQ is working well with my indicator bouncing between 0 and 1. I should also mention I am using the 10% bleach from HD and running my pump 24x7, so high flow may not necessary for my application.

My gauges are working. In addition to the gauge at the top of the filter I have a more expensive pressure gauge on the filter inlet pipe which ranges 0 to 15psi. The two gauges together move in tandem consistently with the filter gauge being 3 psi lower than the line gauge. I don't know if this represents a 3 psi drop between the inlet pipe and the filter or if the filter gauge is just 3 psi off.

I am trying to make my 4x160 at speed 2 work with the LQ. If I crank it up to speed 3 then my filter pressure is the same as others on the forum (10 - 13 psi when clean).

My runs are actually quite long (80 to 160 feet) but my system is all 2 inch and everything is run in parallel so head is very low. My 14 wall returns are actually (7) 2 inch pipes with 2 returns per pipe all in a manifold. The 13 floor returns are (4) 2 inch pipes with 3 returns on each pipe except one which has 4 returns all in a manifold. The two manifolds are valved together so that I direct water to one or the other exclusively or both at the same time. I am using very small return fittings on the walls; generally 1/2 inch but the floors have large area returns.

A picture would be much better; I am working on it. Unfortunately disaster had to strike when I was so close to finishing. My autofill line is leaking at the 90 going up into the fill. The good news is that it is repairable if I can reach it. The bad news is that its 38 inches under the deck. I have long arms but not that long.

 

[mas985]

My gauges are working. In addition to the gauge at the top of the filter I have a more expensive pressure gauge on the filter inlet pipe which ranges 0 to 15psi. The two gauges together move in tandem consistently with the filter gauge being 3 psi lower than the line gauge. I don't know if this represents a 3 psi drop between the inlet pipe and the filter or if the filter gauge is just 3 psi off.

I would expect less than 1 PSI difference betweent the pump and the filter PSI so I suspect that the filter guage is off. One way to check is to swap the guages and see if they read the same.

 

[tmoss]

I run 25 gpm through my quad 100 at 0-1# after cleaning it. I disagree with Stever. If the filter pressure never changes then how can it be getting dirty enough to clean? Doesn't dirt = restriction? Maybe I'm missing something. I do agree that a lot of media and dirt do settle on the bottom of the filter case. Over time the pressure on mine does rise as the dirt load increases. What I have noticed is that the pressure and watt reading remains constant for several weeks after cleaning and charging the filter. But as the filter starts to get dirty this is what happens: In the morning it will be low (along with a corresponding low watt reading). But as the day progresses and the media and dirt get agitated within the filter, the pressure, along with the watts, rises. This happens repeatedly. I set my filter percentages on a 10# scale so when it reads 20% dirty that equates to a 2# rise on my filter pressure. Sure enough the gauge will read 2-3#. And my watts go from 165 to 230 or so. This rise usually takes 3-8 months. At this point the intra day variability is a few percent and maybe 10-15 watts. I realize everyone's pool is different. However, this same exact scenario has repeated itself 3 times (pool is 17 months old). And, based on what I've witnessed with my pool, low pump rates through a large filter yield excellent economical results.

 

[stever]

Well, I could be jumping the gun on the cleanings too. Only been cleaned a few times. Seemed pretty nasty when I opened it up, but it could have had another few months in it. I'll watch it more closely, but can't remember the pressure changing -- even after hte pool was new and it sucked up all of the plaster dust... It is a pretty large filter, though...

Are you really running 0-1psi (clean)? are you running it through the heater, etc, also? I know I don't have the most efficient supply/return, but I'm a bit jealous if you!

Steve

 

[tmoss]

I believe my gauge to be accurate based on the pump curves I obtained from Pentair and real-world response in pump rate and filter condition changes. I also have a looped 2" return for less restriction. Additionally, I elected not to have a heater in part because of the added head pressure that results. I didn't think that the heater, if installed, wouldn't be used more than two months out of the year. And bypasses just add more pressure.
I would think that you would see a pressure decrease after a filter cleaning. If not, and your gauge is working properly, then the filter isn't dirty. Or not dirty enough to decrease the load on the pump (lower head). That said, prematurely cleaning a quad does give one the satisfaction that the pump is always dealing with minimal head (mainly what's inherent with the plumbing, etc). But it comes with the added expense of using more DE and the time involved for the cleaning. If you're interested in trying to save kw costs then I'd recommend only filtering the volume necessary to keep the water thoroughly sanitized and clean. Every pool is different. For mine, I'm now down to 13k on a 26+k pool. In the summer I run 21k. I know that the usual recommendation is at least 1 turnover daily. Now, I've only been a pool owner for 17 months, but this protocol is working for me.

 

[carlos31]

Well, I still don't have the pictures, but I did fix the autofill. Dug out a hole big enough to get under the deck and found that I dry fit the pipe but must have forgotton to glue it.

The good news is that makes for an easy fix. Everything working now; except my camera.