Sand filter high pressure: backwash does nothing

[stephen11962]

Tagelus TA 60D sand filter, 6 port valve, 5 years old, low load - 2 people, on/off pressure differential = 18 psi. Backwashing/rinse cycle makes little difference. I do not accurately remember last years reading, but this seems much higher and there is a marker ring on pressure gauge that says "clean" after 10 psi differential.

I tried using a chemical sand cleaner (GLB Filter Fresh), but may have inadvertently left timer on and short circuited the procedure. But: The procedure for filling the tank with the cleaner seems to me to be very imprecise; empty tank, pour in cleaning solution into opened lint pot with pump on, shut pump and wait 12 hours. The instructions are for all tanks regardless of size. So, I do not know how much of the sand is actually covered by the solution. Tagelus manual is very vague about this and tech support even vaguer.

I have seen reference to removing the valve and manually agitating the sand. I see no way of doing this without cutting all (except pipe to pump w/ union) all connecting pipes. (Is there a industry standard for installing unions to facilitate servicing?)

So, do I re-try the chemical cleaning (and do it right this time)? How much do I use? Is there a 'best' product for this? Other solutions?

TIA

Stephen

 

[JasonLion]

Welcome to TFP!

It is very unlikely that chemical sand cleaners will have any effect. They are mostly a waste of time/money.

There are a couple of possibilities as to why the pressure is so high. The gauge might be broken. Check the return jets, if they are weak then the pressure probably really is high, but if they are as strong as usual the pressure gauge is probably broken.

There might be a blockage in the plumbing somewhere other than the filter. Put the main valve on bypass and check the return jets. If the jets work on bypass and are weak on filter then it is the filter, but if the jets are the same in both positions the problem is elsewhere.

If both of those checks point to the filter, you need to open it up and see what is going on inside. When you have a top mounted multi-port valve you always want to use unions on the plumbing so you can open up the filter.

 

[jblizzle]

What do you mean by 18psi differential? Does the gauge go to zero when the pump is off?

Also we recommend cleaning when the pressure rises 20-25% over the clean pressure, not a fixed 10psi.

Sounds like you will have to cut the pipes and add unions.

 

[stephen11962]

I have been a known lurker.

Answering the questions:

Gauge with pump off = 0
Gauge with pump off = 18


One possible conclusion about the gauge is that it is not completely broken, but could be giving exagerated readings?? I have no expertise in pressure gauges.

And the return jets are strong.

Stephen

PS
Adding:
Gauge with pump on filter = 19
Gauge with pump on recirc = 18
And the jets seem a little stronger during recirc, which makes sense, not having to push past the sand.

Does that mean the gauge is off? Or what?

 

[macgulley]

My normal running pressure is 20 psi. I try to clean when it goes above 25 but it has gotten as high as 30 before. I wouldn't be concerned about 18 psi. You should backwash when it reaches about 23.

 

[jblizzle]

So the gauge reads 19 with pump on in filter setting. You turn off the pump and gauge goes to 0. You turn the valve to recirculate. Turn the pump back on and the gauge reads 18??? That should not be possible since in recirculate the filter should be bypassed and see no pressure.

 

[JasonLion]

There will always be some pressure, often most of the pressure, when running on recirculate. Much of the dynamic head comes from pushing water through the pipe from the filter to the pool.

From the sound of things the gauge is broken such that it more or less tracks the pressure but reports higher than actual numbers.

 

[jblizzle]

There will always be some pressure, often most of the pressure, when running on recirculate. Much of the dynamic head comes from pushing water through the pipe from the filter to the pool.

Sure there is pressure in the plumbing, but if the pressure gauge is on the filter (like I thought most were), then it should not read any pressure while on recirculate. I could have the top of my filter with the gauge off and sitting on the ground and still run the pump on recirculate ...