High pressure low flow

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SirSwimAlot

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Jun 1, 2016
133
East Coast
I was opening my pool and it was really bad algae as usual, so I ran the filter and after I got things fairly cleaned I did a backwash. I got lazy and didn't turn the pump off and just switched from backwash to rinse one or twice near the end. After that I started leaking water fairly quickly. I remember last year I had same problem and was going to replace gasket but when I did I noticed it was really twisted in one spot and the gasket was not coming for a day or so, I reseated it and lubed and put things back together and it was all fine, so I never bothered to replace the gasket.

This year after moving the filter without turning off the pump I had 20+ psi after a backwash. So I replaced the spider gasket and I still had leaking. So I redid the gasket this time with silicon on the bottom (I've used just lub in the past). At this point I took apart the DE filter and hosed down the filters. After putting things together, I had no more leaking, but I had high pressure 20 psi at start, then it went up to 30 psi. I vented the filter until I got just water and reseated the gauge and hit the button on it before rescrewing it in.

I don't believe I had high pressure before moving the filter dial while the pump was on but I am not 100% sure. I'm pretty sure I did not because I remember the jets were pushing stronger. I did leave the gauge out over the winter by accident, I usually bring it inside. I don't think this is the problem though.

I do have flow from the jets, but not as much as I usually do. I don't see any visual leaks anywhere.
 
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It sounds like you've had several issues that required attention. But the slower water flow and higher filter pressure sound like they are related to algae. Can you post a full set of water test results? That would be step one before we start evaluating mechanical issues.
 
I would only take the CYA up to about 30-40, and leave the pH alone for now. Feel free to increase the FC anywhere between 7-9 today which I suspect the water could use after opening. This evening do an Overnight Chlorine Loss Test just to be sure you are 100% algae-free. You'll have better peace of mind.
 
Algae could cause the pressure to be that high? Even when the water looks really clear? I have no doubt there might still be algae in the water, (it looks crystal clear) but I'm still finishing the opening. It looks really good though, so I don't understand how it can cause so much pressure and slowdown of flow. Would the algae be somewhere else in the system? I hosed down the DE grid really well.
 
SirSwimAlot said:
Algae could cause the pressure to be that high? Even when the water looks really clear?
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Absolutely. Not all algae pools are a green swamp. Transparent organic matter can easily overwhelm a pool filter causing a spike in pressure. Accurate water testing with a TF-100 or Taylor K-2006C test kit is often overlooked by many until they hit a wall of frustration. :brickwall:
 
SirSwimAlot said:
I just measured and the loss is around 0.5 fc.
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That's good. As long as the FC was no more than 1 ppm overnight in hours of darkness you appear to be algae-free. If ever in doubt, that's the test to do.

So now the pressure. If water flow still appears low and pressure is high, there has to be something going on in the filter. Even if teh gauge was going bad it wouldn't effect the flow, only give a false high reading.
 
Texas Splash said:
That's good. As long as the FC was no more than 1 ppm overnight in hours of darkness you appear to be algae-free. If ever in doubt, that's the test to do.

So now the pressure. If water flow still appears low and pressure is high, there has to be something going on in the filter. Even if teh gauge was going bad it wouldn't effect the flow, only give a false high reading.
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I took the filter apart and washed it good, and it looks clean. The breather was dirty which I washed, but didn't take off, not sure if you have to clean inside of it some how. Can anything in the multiport valve cause high pressure? I figure it can cause low pressure if it leaks to waste or something, but can it cause high? This seemed to happen after I moved the multiport while it was running and have since replaced the spider gasket (we have had problems with this before causing a leak as described above) but wondering if it can cause high pressure, if not that mostly means it is the de filter only, unless something in the pump but the pump is brand new (last year).
 

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It wouldn't be the pump, that's for sure. The MPV could effect water flow being low as you noted. High though? It would seem odd since water goes through MPV first, High pressure would seem to be after the MPV. But it is odd that you seem to recall the high pressure issue happening after messing with it. :scratch:
 
Texas Splash said:
It wouldn't be the pump, that's for sure. The MPV could effect water flow being low as you noted. High though? It would seem odd since water goes through MPV first, High pressure would seem to be after the MPV. But it is odd that you seem to recall the high pressure issue happening after messing with it. :scratch:
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I didn't do anything with filter but backwash it. The pool was leaking, and had high pressure, so I tore the MPV apart as I have had issues with the spider gasket before, and I held off replacing last year as the leak stopped.

I washed the grid inside of the bottom half of the DE filter with a hose, we did a good job of washing it down but didn't take the grid outside of the bottom shell. Is it possible this could be the problem? Basically we took top off, hosed it down really good let it drain from bother and hosed down the breather which was gunked up and put top back on. Is there something I can look for to confirm where the problem is?

It's a big pool and thus a big de filter, which I assume is going to be on the upper end of costs to just replace. The grid didn't show any visible damage.
 
SirSwimAlot said:
but didn't take the grid outside of the bottom shell. Is it possible this could be the problem?
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It could be. At this point, before spending more money/time on parts I would definitely strip that filter down to the core. Be careful. I don't need to tell you that DE grids/fingers are sensitive buggers and can get damaged along the way. Take your time, but give it a thorough inspection.
 
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