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Thread: Backwashing

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    Backwashing

    I am new to having a sand filter. Is it normal to have to backwash after every vacuum. The pool has only been up 2 days and both days I vacuumed and both times I had to backwash. After vacuuming the filter strainer on the pump was full of water. Usually when I run the filter there is no water in there. I turned the pump back on after vacuuming and the water was still there and it didn't look right so I backwashed and it did go away. The following day same thing. Is this normal or am I doing something wrong?
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Richard320's Avatar
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    Re: Backwashing

    The strainer in the filter is supposed to catch leaves and stuff. You just unscrew the lid and lift the basket and knock the stuff out. Looking through that clear lid you should see water. Solid water, with maybe a small air bubble trapped against the lid.

    If the pool is only two days old there shouldn't be enough in it to clog the filter for weeks. Something is not right. Maybe you plumbed something backwards?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: Backwashing

    That's what I'm wondering too. I don't see water going through it during normal filtration. Only when I hook the vacuum up.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Re: Backwashing

    This is the strainer. When the filter is running there is no water in it. You see what looks like dust floating around but that's it. When I vacuum it does fill with water. Once I stop vacuuming and just filter the pool there is no power and that strainer is still full of water so that's when I backwash it and the water goes away and my power is back. filter.jpg
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Richard320's Avatar
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    Re: Backwashing

    I wish that picture was taken from further back so we could see where the hoses go. But regardless, the pool water level is above the pump, so it should be air-free just sitting there.

    If you have the new style intex with dual inlets, they go to the hose coming out the nose of the pump. The hose coming out pointing up goes to the filter inlet, and the filter outlet goes back to the pool.

    My knowledge of intex vacuums is nil, so I can't say whether or not the vacuum is supposed to connect to the suction or pressure side.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Backwashing

    filter 3.jpgDoes this help?filter 2.jpg
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Re: Backwashing

    As far as the vacuum I connect it to the intake in the inside of the pool.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Richard320's Avatar
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    Re: Backwashing

    It looks right. Are those plunger valves where the hose connects to the pool wall open all the way?
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Piolin's Avatar
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    Re: Backwashing

    In the first picture in post 6 I see the valve closed, could this be the problem?
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    Re: Backwashing

    No that's open. Both valves are open.

    - - - Updated - - -

    If I put my hand inside the pool I can feel the water sucking in and blowing out the out.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Re: Backwashing

    OK, maybe I am looking at this wrong, but when you say that there is "dust floating around" how is the dust floating around if there is no water. I coudl be completely wrong on this, but are you sure there is no water. Or is there any chance that it is 100% full of water, and because there are no air bubbles or gaps, that you cannot tell if there is water or not?

    You also say that "Usually when I run the filter there is no water in there". 100% of the water should be going through the filter basket, I think. Of course I coudl be way wrong on this, in which case, I apologize, please ignore me.

    - - - Updated - - -

    Also, am I looking at your pump wrong?
    I am going to make 2 assumptions

    1.) I am assuming that the fitting on the wall of the pool that is lower is the return, and the one that is higher is the skimmer.

    2.) I am assuming that the flow of water should be as follows:
    a. Water goes from pool into skimmer
    b. Water leaves skimmer and goes to pump
    c. Once in pump, water goes into the skimmer basket.
    d. Water goes through skimmer basket and exits pump
    e. Water enters multiport valve
    f. Water can go either into pump and then back to pool, or straight into the pool.

    If that is correct, then I think that skimmer and return are hooked up wrong.

    But as is above, I could be wrong, and if so, I will use this as a great learning tool.
    IG W/Vinyl Liner Oval 18x40, 21K gal, Oval 3'-8'
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    Re: Backwashing

    When I get home I will physically pull the top of strainer off to double check there is actually no water in there. I am 99% sure I am correct though. When I vacuum you can actually see the water moving around in the filter basket but not when it is just filtering normal. It looks empty. To answer your questions Yev if your facing the pool the hose on the right which is lower is the intake. The water sucks in that hose then it's I'm assuming suppose to go through the skimmer basket and filter and then it shoots out the hose on the left which is the higher of the 2. The return hose. That part doesn't seem to be an issue.

    I actually just watched a you tube video of someone demonstrating my filter and there filter basket looks the same as mine. I'm more concerned now with the filling up when I vacuum and then having to backwash daily to get the filter back running correctly. Nothing big goes into my filter basket since the strainer on the end of my intake seems to stop it all and stays in the pool instead. It can't be removed. Seems a little silly the way they made it. That's another problem with these intex pools that I'm aware of.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Richard320's Avatar
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    Re: Backwashing

    You know what, it sounds normal. The vacuum and the hose restrict water flow. Your pump is likely cavitating. Mine does a little when I vacuum.

    Check it out. You'll need a helper. Hook up the vacuum and let it run until you see the water sloshing in the pump strainer basket. You watch the pump and filter and the helper disconnects the hose. Does the water level rise in the basket and the bubbles shrink and disappear? Does the filter pressure jump almost instantly as soon as the vacuum, gets disconnected? If so, it's normal and what it really means is that your water is clear enough that you can;t see it. And that your connections are airtight.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

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    Re: Backwashing

    Quote Originally Posted by brickladyt View Post
    No that's open. Both valves are open.

    - - - Updated - - -

    If I put my hand inside the pool I can feel the water sucking in and blowing out the out.
    This is when your in filter mode, correct ? If you feel suction at the intake and strong return flow, then I think it's working.

    Like Richard said, I also have cavitation when running my vacuum and you can "see" water moving. When in filter mode the strainer is full with no bubbles, so it looks like there is no flow, except if there is any debris in there you can see it "floating" around
    Si -central Mo. 32' x 16' -- 3'4" to 6' deep Vinyl liner - 16,500 Gals : Triton II filter -Duraglass 2 hp pump - 1 speed : SI-30 salt generator
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    Re: Backwashing

    Ok I will do that and note what happens this afternoon. I do remember the first time I used the vacuum once I was done I had no pressure shooting out of the return flow and that's when I noticed all the water in the basket so I backwashed it and it was fine after that. The second time when I saw the water I just automatically backwashed it. I didn't feel the return flow. I'm at the point of just buying a battery operated vacuum so i don't have to even worry about this issue anymore.

    Just to confirm I am suppose to vacuum in filter mode correct?
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    lefty51's Avatar
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    Re: Backwashing

    Yes, you vacuum in filter mode. If you have a waste setting you can vacuum in that mode to bypass the filter, BUT you will lose water that way. Usually you would use that if your pool was filled with a lot of gunk and you wanted to get rid of it instead of just filtering it. Normally just filter it. When you say you have to backwash everytime after filtering is it because the pressure jumps up that high after vacuuming ?
    Si -central Mo. 32' x 16' -- 3'4" to 6' deep Vinyl liner - 16,500 Gals : Triton II filter -Duraglass 2 hp pump - 1 speed : SI-30 salt generator
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    Re: Backwashing

    Quote Originally Posted by lefty51 View Post
    . When you say you have to backwash everytime after filtering is it because the pressure jumps up that high after vacuuming ?
    No because the filter doesn't seem to go back to normal cycling again. The return jet has no power again until I backwash.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    Re: Backwashing

    I turned the pressure release at the top of the strainer and water came out so it looks like there is water in there. I guess it's just so clean I couldn't see it.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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    lefty51's Avatar
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    Re: Backwashing

    Quote Originally Posted by brickladyt View Post
    I turned the pressure release at the top of the strainer and water came out so it looks like there is water in there. I guess it's just so clean I couldn't see it.
    That's good ! and you also feel water returning to pool ?
    I'm still puzzled why you have to backwash to get flow again, though
    Si -central Mo. 32' x 16' -- 3'4" to 6' deep Vinyl liner - 16,500 Gals : Triton II filter -Duraglass 2 hp pump - 1 speed : SI-30 salt generator
    TF-100 with speedstir

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    Re: Backwashing

    Yes I feel the water going back in. I'm going to try loosening the air valve on the strainer the next time I'm done vacuuming to see if that makes a difference. Unfortunately I didn't have time today.
    18x48 ultra frame AG Intex pool 6423 gallons
    Krystal Clear Sand Filter Pump Model SF70110
    Test kit - TF-100

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