sand filter questions

[Johnny B]

I am new to sand filter use, (had a DE filter before )
I have question re sand filters
With fresh new sand, the psi was 14, so that is my normal starting pressure. It is 14 if only the drain only is open. If skimmer only or both skimmer & drain are open (the usual scenario) the psi is 18. Both starting points are ok with respect to when I need to backwash? I can just go 10psi or so beyond either # depending on what is open .

Wash glass or whatever the term is, the glass like bubble that you look at to see when the water clears. It unscrews, for cleaning? Can leak/sputter water just a tad (doesn’t bother me), any worries. You guys ignore it & look at the water exiting to waste to see when the water is clear? When the water starts out clear but the psi indicates backwashing (so there is no “water to observe go from dirty to clear) you go by how many seconds in my case? (hate to waste the water). I just keep testing/reducing backwashing time to see how quickly I can get to the start 14 psi, right? To date, with heavy opening debris, it takes maybe 20-30 seconds. The manual says backwash 3-5 minutes!? I'll be adding an inch of water ( I Exaggerate).

At this startup, 2 or 3 times when the psi was up & indicated for backwashing, the pump basket had maybe ¼ the water it should!. Can’t be good on the motor, or is it ok. I don’t recall way less water in the pump basket with my old DE filter when the pressure rose.
You guys like to Rinse 5-10 seconds after each backwash, right?

No need to use the air relief valve? You never do when it starts from a timer? Or you use the air relief valve only when it starts out dry (no water, & water is added for the 1st time at the 1st startup of the season or with new sand)? Or you use the air relief valve only when the pump basket comes off for cleaning resulting in some air getting in the lines?

Best to try to always move the MPV in the same direction?

When is the "Closed " position on the MPV used ( I realize no flow & never w pump running)
Any other trips welcomed too.
Thanks

 

[Bama Rambler]

Yeah 10 psi above normal, so if it's normally 14 with the main drain open then it's 10 above that.

The clear bubble is also a vacuum relief valve on mine and once in a while it'll drip/sputter a little water.
Because mine is plumbed into a drain I use the bubble to tell when the backflush is clear. It always starts out clear but soon clouds up as it starts flushing dirt from the sand.
I rinse until the water in the bubble is clear.

Actually when the pressure on the filter goes up the pump should be moving less water and therefore have less suction pressure so the basket should remain full.

I've only used the air relief valve a few times, like when I knew I had introduced air in the pump/filter. Even then it'll purge it out after running a few minutes.

Can't comment on the last two.

 

[bk406]

Best to try to always move the MPV in the same direction?

I dunno, maybe an old wives tale. I generally turn mine in the same direction. It goes both ways, but I'm in the habit of going clockwise with mine.

When is the "Closed " position on the MPV used ( I realize no flow & never w pump running)

Put it to close when you close down and winterize for the season.

 

[JasonLion]

Closed is normally used when your equipment is below the level of the pool water. In that situation you turn the valve to closed when you are opening the pump strainer basket so the entire pool doesn't try to drain out through the strainer basket. This isn't important if your equipment is above the level of the pool water.

For winterizing there is often a winterize position on the valve.

 

[New2Me]

I used the "closed" position every time I open the system. I turn off the pump, closed the inlet suction valve and turn the MPV to "closed." Now you can open the pump, empty/clean the strainer basket, or check/clean the ECG cell and not have the filter siphon itself empty. Close everything back up and open the valves right before you turn the pump on, and the prime time is almost zero, because the piping is all still full. If it won't stay full, time to start the leak hunt!

 

[Johnny B]

Actually when the pressure on the filter goes up the pump should be moving less water and therefore have less suction pressure so the basket should remain full.

Just so I'm clear, ...so the basket "wouldn't" remain full?
I never noticed this on my old DE filter. I just assumed that if that basket wasn't full that it was harmful/stressing the motor. I guess so long as there is SOME water flow the motor is ok?

 

[JasonLion]

Normally, the pump basket should be full of water, or have one small bubble. Usually, if there is a lot of air in the pump basket, you have a problem. However, now and then there can be a significant amount of air in the basket even when everything is fine (but that is kind of unusual).

 

[Johnny B]

Normally, the pump basket should be full of water, or have one small bubble. Usually, if there is a lot of air in the pump basket, you have a problem. However, now and then there can be a significant amount of air in the basket even when everything is fine (but that is kind of unusual).

The air is only when it is time to backwash, & not 1 or 2 psi earlier. What is your diagnosis? FWIW, the water level can get 1/2-inch too low at times


Backwashing questions:
1- if you backwash & upon resuming filtering, the pressure returns to the hopeful expected starting psi, you have backwash successfully or not necessarily? Reason I ask, I can’t really see “dirty water going to clear” either in the bubble or out the pipe, it all looks clear to me from the go. I have been backwashing about 12-15 seconds & each time, the pressure lowers to the ideal start pressure. The manual said Bwash 3-5 min. What do you guys find (so many variables for sure)

2- Simply turning the pump Off ( no backwash or anything, just Off), doesn’t affect the pressure the next time it starts up, does it? Suppose your range is 10-20 psi, you turn the pump off at 15 psi (so not time for the 20 psi backwash) for a few hours; at the re-start, the pressure should be 15psi, or it doesn’t necessarily work that way?

Thanks

 

[JasonLion]

You need to backwash much longer. When you first start backwashing you will get clear water. It can take 10 to 30 seconds for the water to turn dirty, once it does it can stay dirty for a while.

 

[Johnny B]

Thanks Jason, a big help as always.
So I backwashed for 30 seconds (night, can't determine clarity) & I didn't have to Bwash again for 3 days. Today I backwashed for 1 minute so I'll be seeing how that does, entire time looked clear to me. Further comments always appreciated.

I am going to edit my posts a different thread based on what I'm learning on this thread.

 

[Molson]

For what its worth, I opened to a really dirty pool this year, been vacuuming every other day since the initial clean up, I've only had to backwash three times. Once the pool is clean, I only back wash when required, sometimes it can go two months, or longer if the water and floor stays clean.