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Thread: low suction and can't vacuum

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    low suction and can't vacuum

    Hi all, I bought my first home and it came with a 20x40 IGP. I'm a total newb to pool ownership and this site has been super helpful. The pool was installed around 20+ years ago and most of the equipment is old. I noticed that the skimmers suction is very very low. Way too low to vacuum. I've tried closing the cover on one skimmer and shutting the main bottom drain but not much improvement. Everything seems to be in working order and my pressure is fine. It's at 20 PSI and was told that once it gets around 30 to back wash.

    Any suggestions would be greatly appreciated.

    Here are a few pic of my equipment set up.
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    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Mod Squad JohnT's Avatar
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    Re: low suction and can't vacuum

    Are you holding the 20psi pressure with the vacuum hooked up and the other skimmer and drain closed? Are you filling the vacuum hose with water before connecting it?
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
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    Mod Squad jblizzle's Avatar
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    Re: low suction and can't vacuum

    Does the pressure gauge go to zero when the pump is off? If not, you need a new gauge.

    You need to know what the clean filter pressure is while in normal filter mode to know when to backwash. You should backwash when the pressure goes up 20-25% of the clean pressure.

    I am wondering if you filter is already clogged and the 30psi advice was wrong.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: low suction and can't vacuum

    The pressure does go to zero when the pump is off and the 20psi is during normal pump operation. I've never checked the gauge when closing one skimmer and the bottom skimmer. I've filled the hose with water before using.

    Here is a pic of a skimmer with the screen out. What's that socket next to the hole for? I had asked the pool guy if I should open and clean/change out whatever is in the big metal canister, but he told me not to and just back wash when the pressure goes above 30psi.
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    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Mod Squad jblizzle's Avatar
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    Re: low suction and can't vacuum

    You do realize that is a DE filter right? When you backwash you have to add DE back into it?

    If it is running after a backwash without adding DE, that is not good and will quickly clog up.

    Did you recently have good flow and suddenly it stopped?
    What does the water look like?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Mod Squad JohnT's Avatar
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    Re: low suction and can't vacuum

    The second hole is for a different plumbing configuration where the main drain flows through the skimmer. Not used in your pool.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

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    Re: low suction and can't vacuum

    I have yet to back wash- the pool has been only opened for two weeks and the water is crystal clear.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Re: low suction and can't vacuum

    Vacuum hose is intact?
    16x32x52" Steel Cornelius Miramar AGP Vinyl liner 13,100 gal. Buried 2 ft.
    2 Speed Hayward Power-Flo Matrix 85 g.p.m. 22" 250lb. sand filter hard plumbed
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    Mod Squad jblizzle's Avatar
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    Re: low suction and can't vacuum

    Are you sure that DE was added at closing? I would recommend a good backwash (maybe even breaking down the filter for a thorough cleaning) and then adding DE to give you a good starting point and a baseline clean pressure.

    I would not ASSUME that the filter was closed correctly ... also not sure how DE could just sit in a dry filter all winter. Or did you specifically add DE on start up?

    If you have been running with no DE, I think you must break it down and clean the grids as they get clogged when there is no DE.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: low suction and can't vacuum

    I did not own the home when the pool was closed so I don't know if DE was added at that time. I purchased the house in late Dec. The guy that has been taking care of this pool has been for 20+ years. He said that most of the equipment was old but functional and that it was pretty easy to maintain. I also don't know if DE was added at opening since I have know idea about pool maintenance. The pool guy showed me the basics on how to test the water, backwashing, adding chemicals, etc. I've been trying to educate myself as best as I can and that's how I found this site.

    Are the skimmers supposed to be powerful enough to run a vacuum? I just assumed so since a 50 foot long hose and cheap basic vacuum came with the pool. I had to buy the skimmer cover. I looked at videos on cleaning pools. When I saw the vacuum not really doing anything, I doubled check to see if the skimmer basket was clogged. That's when I noticed the skimmers not having much oomph.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Mod Squad jblizzle's Avatar
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    Re: low suction and can't vacuum

    Are there valves at the pad to adjust where the suction comes from?

    I still am leery of the condition of your filter. If it is clogged then there would be low flow.
    My first recommendation is break down and thoroughly check the filter grids since at this point the condition is VERY unclear.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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    Re: low suction and can't vacuum

    Ok, thanks for the suggestion Jason. I'll talk to the pool guy about doing that. I've done some research on it and it seems like I should watch someone do it first before I give it a try. I did mention it to him and he said it was pain since you need to reseal the metal container and whatnot. Does it matter that my container is a super old version if I need replacement filter grids?
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Mod Squad jblizzle's Avatar
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    Re: low suction and can't vacuum

    At a minimum take the top off and see what is going on in it.

    Just turn the pump off, open the air valve on the top, and then take the top off. If they are old, and not often cleaned, they could probably use a good soap soak and then acid wash.

    I think there should still be grids available.

    So, have you had good flow at ALL this year? Post up more pictures of the valves and pipe around the equipment so we can see if anything is obvious. In either case, you need to learn how to maintain the filter.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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  14. Back To Top    #14

    low suction and can't vacuum

    I had this same exact issue at the beginning of the season due to a clogged filter, I would do what these guys have recommended and there's a good chance that will solve your issues, might just need a good backwash?
    18' x 33' Aqua leader AGP (~19k gal) w/hayward swimpro voyager cartridge filter and 2hp hayward pump.
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    Re: low suction and can't vacuum

    I'm going to backwash this weekend. We're supposed to get heavy thunderstorms tomorrow anyways, so I'll need to lower the water level. Been looking at videos on how to clean out the DE filters. Doesn't seem to difficult, just need to find the time to do it.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Re: low suction and can't vacuum

    It's amazing what a difference a backwash can make for the functionality of the main filter/pump system. A modest increase in pressure can lead to a significant decrease in flow rates, as I just observed last weekend. Our pool had been starting to get some spot algae (yellow/mustard) on the walls, and I kept adding lots of chlorine. I would brush every day, and yet it kept coming back. I noticed that the MX8 autocleaner was acting listless. Despite cleaning it out, it remained listless. So, I backwashed and the pressure dropped from 25 to about 15. I didn't want to break the filter down, so I did my typical backwash where I cycle the filter valve between backwash and normal about 3-4x. This tends to get nearly all of the filter media pumped out. I then restocked the filter with cellulose DE replacement. I couldn't believe the difference in flow rate. The MX8 sparked back to life and the skimmer and surface flow both looked much better. I'll try to be a little more cognizant of this.

    If backwashing doesn't fix this, you might have a pump issue, or there could be something trapped in the vacuum line. Does your pool have an attached spa? If so, do you see that moving the suction side 3-way valve to the spa line affects the flow? Do you have a drain vs. skimmer valve? If so, do you see a difference in flow rate by moving that valve from one side to the other? If you do, this would suggest a clog in the skimmer vacuum line. If not, I'd be checking the pump to ensure that the impeller is in good shape.

    To answer your question, yes, the skimmer typically has enough flow to connect up a pool vacuum and clean the floor and sides.
    38K in ground pool with attached spa. Current equipment: Easytouch 8 (521150) with IC-60 SWCG with web control by Autelis, 1x Pentair IntelliFlo 011018 pump (for filter), 1x Pentair 2HP WhisperFlo pump (for waterfall), 2X Pentair IntelliBrite 5G 12V lights, Pentair MiniMax400 NG Heater, Pentair SMBW2060 DE filter. Zodiac Barracuda MX8 cleaner on dedicated cleaner line. Lighting/home automation controlled by Insteon/ISY-99i.

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    Re: low suction and can't vacuum

    No attached spa. The pool guy told me that 20psi was normal- it's up to 25-26ish after about 3 weeks. It never had much suction since the day it was opened. I do have different lines and valves that are labeled bottom and skimmer. I'm assuming that's what you're talking about. How do I check the flow rate?

    I'm definitely going to do the backwash the way you mentioned this weekend and I'll report back. I did purchase a new O-ring just incase I decide to try and open the canister. I've also located a manual for my DE filter and getting up to speed on how to mantain it.

    Thanks all for your feedback and will let you guys know how the backwashing turns out in a few days.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Re: low suction and can't vacuum

    Well I did my first back washing. The manual said to cycle back washing (30 sec) and running the filter (1 min) 2-3 times. Since my water level was high from a recent storm, I did this about 8x until the water level was at the correct height. I really didn't notice the back wash water dirty or much DE coming out and wasn't expecting any improvement. However, after adding in DE and airing out the bleed valve- a huge difference! Suction was much stronger and even the returns were pumping with greater force/volume. I tried the vacuum but needed to shut the main bottom valve and the other skimmer for it to really work. My psi is back to 20. I think I'm going to open up and try to clean the screens at the next back washing. I purchased a new O- ring, lube, and DE filter cleaner. I also have an order in for new filter screens.

    Thanks all for the guidance! I'll update once again when I clean filter screens.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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    Re: low suction and can't vacuum

    You should get in the habit of doing a complete tear down and cleaning of that filter once a year. Washing the grids and soaking them in a dilute solution of acid is also a good idea.

    Once you do this (admittedly a pain) you'll know what the clean pressure is and will subsequently know when to backwash
    In the industry, CSP (Certified Service Professional) by the NSPI and it's successor the APSP. My company services over 600 pools every year. I think the practices regularly espoused on this forum (especially the BBB method) are outstanding; however my comments will be often oriented towards the goal of getting it done, and getting it done right now!

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    Re: low suction and can't vacuum

    Well I finally had some free time this weekend and took a stab at opening up the D.E filter. I had purchased a set of replacement fins and O-ring just in case I messed up. My plan was to clean the old fins as best as possible. I even purchased some special detergent to soak them in. After opening the can and pulling out the filters- I quickly decided to just replace them. They were a dark brown color and a few had holes in them. Sorry I didn't take pics. It was a pain getting everything back together but after a few tries (and some cursing) I managed to do so. Had just the right amount of D.E. on hand to coat them. Everything seems to be working just fine. I would of thought my starting pressure would be lower but it's at 20psi like before. Suction is great and returns are strong. Now my mind is at ease knowing that's been taken care of.
    20x40 IGP - Nautilus NS36 DE Filter - Haward 1 1/2hp Super Pump - Haward Multi Valve

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