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Thread: Can't get sustained suction for Vacuuming. HELP!

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    Can't get sustained suction for Vacuuming. HELP!

    This problem has been puzzling me for years now. I can't seem to get sustained suction for vacuuming. If you look at the photo, you can see our pool has a simple setup. One inlet and 3 return jets. The pump/filter is located about 29 feet from the inlet. I have a vacuum plate that is on most of the time, and I usually insert the vacuuming hose directly into it. Lately, I've tried removing the plate, and inserting the hose directly into the inlet.

    It seems that the problem I have, no matter what configuration - is that I only get about 10 minutes of really good suction off the hose. This happens with both a hand vacuum (on a pole) and a Kreepy Krauly. When you first hook up either, it sucks like gangbusters, but then tapers off. What's strange is that even when I'm not getting good suction from the hose, you can still see water coming in through the pump, and there is water surging out of the outlet jets.

    Any help would be appreciated - If I could only have good, sustained suction for 30-45 minutes at a time cleaning the pool would be a much easier task

    Thanks!
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    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    mas985's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    One problem vacuuming directly into the pump is that the pump basket will quickly fill and reduce suction. Also, debris could get caught in the pump impeller and reduce flow rates. Vacuuming through the skimmer basket is a bit better and can prevent some of these problems but even that will need to be emptied often if vacuuming a lot of debris.

    A few questions:

    What is the filter pressure with and without the cleaner?

    Does the PSI change while vacuuming and is the pump basket fill up with debris?

    Is it any better right after a filter backwash?

    Is your plumbing 1 1/2"?

    Do you also have a main drain?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Mod Squad JohnT's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    If the skimmer is the only source of water for the pump, you can starve the pump when you add all the hose. There are skimmer vacuum plates that have adjustable holes in them to allow some water to bypass the vacuum to keep the pump operating. You can also just get a conventional skimmer plate and drill holes in it until it works for you.
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    Re: Can't get sustained suction for Vacuuming. HELP!

    I just ran the Kreepy with the skimmer plate on and the leaf basket in the skimmer - normal operating conditions. I had suction for about 15 minutes and then Kreepy stopped. Here is some other info.

    1. Pressure at normal operation - 10-12psi
    2. Pressure with operating vacuum - 8psi
    3. Pressure after 15 minutes with no vacuum - 20psi
    4. 1 1/2" plumbing
    5. Main drain blocked when vacuuming with skimmer plate turned to "vacuum" position
    6. Backwashed

    I'm not vacuuming any big debris or leaves, just dirt.

    I wonder if the problem is like JohnT proposed, that there's only one source of water for the pump, so the 10-15 minutes of suction is all that I'm going to get?
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    mas985's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    If your filter pressure goes from 10 PSI to 20 PSI, the suction will drop dramatically with or without the cleaner. I think you are simply overwelming the filter with dirt. Are you opening the pool or is there a lot dirt you are vacuuming up? If so, you might want to vacuum to waste until you get most of it up.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Can't get sustained suction for Vacuuming. HELP!

    There's not that much dirt, just a normal accumulation. Lots of pollen falling in Texas lately. Just trying to keep things looking nice since it's warm here - not swimming yet.

    But just for my education, with the setup I've got, would it be normal to be able to run the Kreepy for hours at a time, or would it overwhelm the pump much sooner. Am I just stuck with the limitations of my setup? If so I'm ok with that, I'd just like to know.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    mas985's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    The disturbing part is the rise in filter PSI in just 15 minutes. That is very unusual and not normal and most likely causing all your problems. Somethiing is plugging up the filter very quickly. If you are not vacuuming a lot of dirt, then the problem could be with the filter itself. Short cycling of a sand filter is usually an indication that there might be something wrong with the sand. Your effective filter area has shrunk quite a bit so you are having to backwash frequently. You might consider taking the filter apart to see if the sand is caked or so dirty that even a backwash won't clean it. If so, you might have to replace the sand.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Can't get sustained suction for Vacuuming. HELP!

    Interesting. Our sand filter is 2 years old, but I have never opened it up to check the condition of the sand. I assume it's not too difficult to take it apart and get to the sand?
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    mas985's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    I wouldn't expect an issue with the sand after only 2 years but I cannot think of anything else which would cause those symptoms unless the filter is just too small. Either you vacuuming up a lot of stuff which is then plugging up the filter or something is wrong with the filter. Given you have had the filter for only two years, it may make more sense that the filter is just too small for the pool and can't handle the little amount of dirt that you are vacuuming. How big is the filter and what is the model# for your pump?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Can't get sustained suction for Vacuuming. HELP!

    The filter is a Pentair TA 40D (40 GPM flow rate) and the pump has an Emerson 3/4 HP motor (MN# K63CXEPW-4765). The filter was a home warranty replacement item, so we didn't really have any choice in selecting it, but it was brand new 2 years ago.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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    mas985's Avatar
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    Re: Can't get sustained suction for Vacuuming. HELP!

    That is a very small filter and the pump is likely exceeding the 40 GPM which could be creating problems with the filter. Also, because the filter is so small, it will get dirty faster which is probably why you are seeing the 10 PSI rise in 15 minutes although that seems too fast for even this filter. It might still be worthwhile to check the sand and make sure it isn't gummed up or calcified. Did you even use Baquacil in this pool?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Can't get sustained suction for Vacuuming. HELP!

    I will open up the filter and see what state the sand is in. After that, I'll explore other filter options if this one is indeed too small to get the job done. I use bleach, not Baquacil, and am having great results with water clarity and am algae free. Thanks for your help.
    11,000gal, in-ground, concrete, sand filter, 3/4 HP pump, TF-100 Test Kit, Austin Texas

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