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Thread: Help!!! I can't reestablish full prime after MFV and sand repalcement

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    Help!!! I can't reestablish full prime after MFV and sand repalcement

    Hello All,
    I am (was)right smack in the middle of a SLAM attempting to clear a pool that was left unattended, and uncovered for over 3 years. (IT WAS REALLY GROSS, but significant progress was being made).

    Something was causing me to lose some water daily, forcing me to top of the pool with water. I had checked all the hoses, around the pool perimeter, etc. and initially couldn't find where the water was leaking from. Then night before last I lost 4-6" overnight. (I thought enough is enough already something must be done to find the problem, and get it stopped).

    I had read an article, (not sure where), that said with the pump off, with the handle in the filter position, to watch and see if the water in the site glass is moving at all, and if so the issue was water being lost out the waste line. Sure enough a little movement was in fact detected, and a leak from the waste line was found.

    Apparently, my old multiport valve wasn't opening, closing properly, or properly sealing into the desired settings that were being selected, so I decide to just replace the entire part instead of trying to pinpoint which piece, or pieces were causing the issue, plus, the PS also confirmed that all the pieces on it were pretty well useless, and would need replacing anyway.

    I decided since that section of the pump was already visible, and I was in a PS who had the supplies, this would be as good of time as any to kill 2 birds with one stone and go ahead, and replace the sand at this time too. Yesterday, replacing the MPV and sand, although very time consuming, appeared to go off without a hitch, or so I thought.


    Plus, because I'd lost so much water, once the new sand was put in, and everything was put back together, it was again time to begin replacing the water I'd lost. (which was a lot). Since I'd put in new sand my pump 1st had to be backwashed for at least 2 mins, and rinsed for 30 secs to a min, before I could turn it to the Filter cycle, and filter the pool. But, my water level wasn't high enough to lose that amount of water out of my pool yet, so I waited, and monitored lines, seals, etc., to ensure nothing was leaking as the water level slowly rose.
    Everything looked fine, no leaks anywhere that I could see.

    The water level got high enough to do the required backwash, and rinse, to seed the new sand in properly, but now I can't get my pump to prime but about 1/2 way, or stay primed to properly get it done. I did do what I could on backwash, and then rinsed a little because I had to try other things to attempt to get the full prime back.

    ALSO my site glass is only about 1/2 full of water when the filter is running too.
    Here's the things I've tried to reestablish prime without success
    1) I ran the pump on recirculate for a bit, it would try to pick up prime, but would then lose it, and blow water and air out the return port.
    2) I opened the drain port at the bottom of the filter which caused the area where the filter basket is at to fill completely up with water, but as soon as it was closed the water level in there dropped to about the halfway mark again.

    The things I've not done that may or may not be causing the prime problem:
    1)I have not dumped water into the actual filter section itself, but it has filled up only to lose prime and drop that water level back to about 1/2, so I don't think a manual prime will help but if anyone who knows a lot more about this stuff than I do thinks it will help, I'll certainly give it a try.

    2)I have not checked yet to see if maybe the impeller is clogged up preventing the water to properly pass through the system maintaining prime, or not, but perhaps that could be a possibility? When the basket was checked yesterday it had very little in it, and Was working fine before the MPV/Sand replacement but perhaps something was in my line from vacuuming that went into the impeller?? (If I check this can I just take off the 1 line where the filter basket is at , and not lose water, or does the return line also have to be removed to keep from getting flooded out?

    3)The only other thing I can thing of that it would be is the O ring, that was put on yesterday is not sealing properly.

    I really know very little about any of this so am I even on the right track with tracking down the non-priming issue? Is there something else it could be that I didn't mention? I really need to get that filter back up and running soon because I really don't want to have to restart my SLAM all over again. Thank you for your help, and have a wonderful day!!
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    If you replaced the top section of the multiport, make sure you put an o-ring on the bottom of that piece since it does not come with one. All your o-rings should be coated with silicone pool lube to help prevent air leaks and ensure a good seal. Make sure the pool is filled higher than normal, about 3/4 up the skimmer opening. Open the pump pot and fill it to the top with water and put the lid back on. Open the filter and fill it with water then close it also. Put the hose still running in the skimmer. Make sure all the valves are open between the skimmer and the return line. Set the multiport to waste. Turn on the pump, use high speed if it is a two speed model.

    You may loose 1/2 the water in the pump pot at first. Keep adding water through the skimmer and keep an eye on the pump pot. It should start to catch up and refill after a minute or so. You need to purge all the air out of the system for the pump to start holding prime. If it is not able to catch prime after a couple of minutes you will need to check for blockages.

    My site glass usually only has a few drops of water in it while it is filtering, so I would not worry about it.
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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Hello crackerjack and welcome, If I understand correctly your pump is not fully priming the strainer basket ?
    If that's the case you either have a restriction (i.e ,valve closed) or you have aleak on the suction side of your pump that is drawing air. When you changed out filter valve and sand, did you disconnect or change anything on the lines running from the pool to the pump, before it goes from pump to filter ?
    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: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Thank you zea3 for your suggestions. Actually I bought the whole entire piece with the MVP on top of it, and it did in fact come with the big round blue O-ring (which I assume is the one you are referring to, Is that correct? or is there another one somewhere else that needs an O ring there too?) I also did lube it before it was put on.

    LOL I'm some of my descriptions of things aren't the exact names. I'm still trying to learn the proper names for the parts so a lot of times I just call it what I think it's called, and then give a description of where its located at to be sure everyone knows what the heck I'm referring to lol.

    I do still have water going into the pool because it was very low, so hopefully, with an overfill we can get this crazy thing to prime, and stay primed, so the Slam can be continued before my levels drop too low.

    Thanks again, I'll let you know how things turn out. I also let you know what ends up fixing the issue lol-hopefully if I can get it fixed. Have a wonderful Day.
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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    Mod Squad zea3's Avatar
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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Yes, that is the o-ring I am talking about. It is difficult to prime the pump when the water level is too low. The pumps push water out faster than they take it in, and if you are seeing a vortex in the skimmer then it is drawing air into the system as well.
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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Hello lefty51. Yes you are understanding that correctly.

    Currently I have no valves on mine to close, but lol if I continue to have to do repairs, or have water leaks I probably should get some lol.

    The hoses were removed from all portions of the pump: Hoses that were connected to the areas marked PUMP, RETURN, WASTE, AND the hose that brings water in from the pool/skimmer to the area where the filter basket is at. I placed the hose that comes into from the pool/skimmer to where the filter basket is at, and also the return hose, over top of the pool to prevent losing water from them while the entire piece along with the MVP on top of it, and sand were being replaced.

    Then the pipes that came out of the old MPV part that I connect the hoses to the pump with were removed from the old MPV, sealed, and placed back onto the new part in the same locations as they were removed from in order to be able to hook the hoses back up on the new one.

    LOL Zea3, I just noticed in my post to you above the abbreviation should have bee MPV not MVP. But I think in this case mine might be a MVP-Most Valuable Player, but right now he's not playing nice at all lol. Thanks again guys I appreciate the help.

    - - - Updated - - -

    LOL lefty51 I did the MVP instead of MPV on yours too. My posts will not save to EDIT it so it's stuck there lol. Hopefully you both know what I mean, lol even I don't. Have a nice day.
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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    Mod Squad zea3's Avatar
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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Ball valve unions are your friend!
    2 Way Ball Valve 1-1/2-Inch Skt - SP0722S Only $ 17.99
    Even better with hard pvc plumbing!
    TFP Moderator
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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Yeah Zea3, I really need to go that way, plus convert to all PVC. Kimkats sent me a link yesterday from Lowe's for something similar that she uses. I'll probably wait until I close the pool down for the Winter, which will be in about 2 months, and convert everything then, or before reopening it next Spring.

    I agree that I really do need those on there though, along with going all PVC, to prevent these types of issues, or a hose splitting in the middle of the night causing tons of water to be lost etc. It will be so much more convenient. Thanks for the Link and I do see this coming in the near future. Have A Nice Day!!
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    By the time you're done, you'll be the MVPO (most valuable pool owner) zea3 will get you up and running, it's either low water level or any lines you took loose between pool and pump (i.e. suction side), double check that everything is tighten down and air tight. Like zea3 said these pumps are made to really "draw" water and if there is a restriction or loose connection they will "pull" in air like crazy. Path of least resistance
    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: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Thank you for the help.

    lefty51, LOL @ MVPO (Here's hopping).

    Houston, we now have contact. Pump is fully primed and filtering at approx. 12-12.5. The water level is nice and high now, which I'm sure helped, but I went back, repositioned and clamped all the hoses going into the pump again as suggested, and just like Magic, full prime appeared.

    A couple of the hoses were sucking air, but IMO the one at the bottom bringing water in from the skimmer/pool to the pump was the main culprit that was sucking the most air in, and preventing full prime. I worked this hose, and all the others I reattached yesterday further up over the connections, clamped them down, then did a backwash, and rinse as suggested.

    Before I did the backwash, I was still only at 1/2 prime, but what I did was actually have the backwash hose up on my tall pool ladder (well above the pump level), so the pump would have to work a little harder, and meet a little resistance, to push the water uphill to do the backwash, allowing for more time down below to reach full prime in the process, instead of the water just quickly passing through at 1/2 prime. (lol I'm not sure this part helped it reach full prime or not, but lol I thought it was a good idea at the time, and something, or a combination of something, worked to achieve the goal, so that's the important part.

    Anyway, so far so good, knock on wood. For now it's doing what it's suppose to be doing.

    zea3 and lefty51, Thank you both for all your help, I couldn't have done it without your knowledge. Have a Wonderful Day!
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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    Re: Help!!! I can't reestablish full prime after MFV and sand repalcement

    When you get done with your SLAM (stay with it like they tell you) and get the feel for testing and maintaining your pool YOURSELF, you will be on here offering the same kind of help. Just watching and reading the posts from these pros like zea3 has taught this old guy all kinds of things and given me the confidence and satisfaction of trying to help others.

    The best advice I got was from Duraleigh , who suggested I post within myself, about things I felt I knew something about. Even if I don't feel confident in the subject, sometimes just offering encouragement behind the pros like I did here can help. In time you will do the same.

    BUT..... first things first, GET back to that SLAM !
    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: Help!!! I can't reestablish full prime after MFV and sand repalcement

    Thanks lefty. The SLAM is underway and In full slam mode once again. I actually did a dirty pump backwash/rinse 5 hours after the filter with the new parts, and new sand were applied, and WOW the difference in the cleaning is unbelievable so hopefully it won't take much longer.


    I understand what you're saying about adding your own comments to posts, or starting your on thread. I actually did one yesterday on using knee high panty hose in the skimmer basket which that little trick has been a life saver for sure. I also posted on 2015 bleach prices thread because my entire Slam has been done using 10% Liquid Shock from Rural King that I am purchasing at 4 gallons per case for $7.99, which is a killer deal. It has saved me a lot of money while trying to get this dirty pool cleaned out. Being disabled, it takes me forever to get anything done anyway because I move so slowly, have to stop frequently, and am so physically limited on what I can do to start with, but the people here have taught me how to raise the FC level high enough to only have to check levels every 3 hours, or less depending on how well it's holding, instead of hourly which has been a big help for me too. I attempted the every hour check but my feet and legs ended up swelling to 4 times the size so that too slowed me even further down and set me back a lot too.

    I've only been on the site right at a week now, but have already learned so much from reading the threads, and from the info offered to me by so many kind people on here. LOL I by far don't have all, or even much of it figured out for sure, but I am certainly a lot better off, and know a little more than I did a week ago, plus I'm sure my pool is thanking me too after 3 years of neglect LOL. I certainly have a lot more questions than I do answers, but I will slowly get there, I hope. Have a nice night, and thank you again for you help.
    24' Round x 4.5 ft deep AGP (15,200 Gallons), Vinyl Liner, Hayward Vari Flo XL Sand Filter- (model SP0714T1),
    TFTestkits , PoolMath , Pool School, RECOMMENDED LEVELS, SLAM & the Chlorine/CYA CHART. Support this Site! TFP Totally Rocks.

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