Backwash Low Flow-not sure filter is working

btpoole

Member
Jun 1, 2012
12
We've had a 24' above ground for about 15 years now. Over this time I have "experimented" with multiple setup. The last couple of years I've been using a sand filter (second hand given to me) . This spring I was gifted a new sand filter (Blue Devil) which came with the multivalve. I also purchased a new variable speed pump. I've set it all up and things seemed to be ok. I had some algae this year as always and proceeded to treat the pool and vacuum the pool as usual. After the process I started to backwash the filter. To my surprise, the flow out of the backwash hose was really low compared to what I am accustomed to seeing. Also the water was not discolored at all, no green or brown coloration. Over the next week I back washed several more times each time low flow and no discoloration. The site glass contents is clear as well. It's almost as if the water is not passing thru the filter at all but just being recirculated back into the pool and the debris in the pool remains. Something else to mention, the pressure gauge never changes, it stays on 0. I have changed the gauge with the same results no matter the setting of the valve. Low flow on backwash and rinse but strong flow when on filter and recirculate. Starting to think the value is messed up. Multi valve pic attached. Any ideas? Thanks
 

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zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
14,213
Houston, Texas
Did you check and see if the sand is at the correct level inside the filter? Did you have to assemble any part of the multiport or did it come assembled? Have you tried running it on re-circulate to see if there is any difference in flow or pressure? How does the flow seem when it is set on filter?
 

btpoole

Member
Jun 1, 2012
12
Did you check and see if the sand is at the correct level inside the filter? Did you have to assemble any part of the multiport or did it come assembled? Have you tried running it on re-circulate to see if there is any difference in flow or pressure? How does the flow seem when it is set on filter?
Not sure of the sand level completely since it was already in the filter when I received it. I will check that first. I did open the top of the multiport when I was getting leakage at the waste hose during the recirulation. I think I got it back on correctly, I matched it to the image I posted as far as it's orientation on the top. As far as the flow, while on filter and recirculate the flow is very strong for both. When on backwash or rinse not nearly what I have experienced on the older filter. I will check the sand level and post back any findings. Thank you
 

btpoole

Member
Jun 1, 2012
12
Looks like sand level is good but all the laterals were sitting on top of the sand and not at bottom of filter. Not sure but I think they are suppose to be below the sand. I dug under neath them and dropped the laterals down as best as possible, I think I got them low enough. Waiting to see if it actually filters. Still not having any luck with the pressure gauge registering. I replaced it again and it registers maybe 1 on any position.
 

zea3

Mod Squad
TFP Expert
LifeTime Supporter
Jul 10, 2009
14,213
Houston, Texas
You need to take out all of the sand and start over. Position the filter where you want it on the equipment pad and remove the sand by scooping it out onto a tarp. Be careful not to break the laterals. Fill the filter 1/3 full of water. Lower the laterals and stand pipe down into the water and make sure the laterals are in the horizontal position at the bottom of the filter. Cover the center stand pipe opening so no sand gets in there. Carefully add sand to the fill line and smooth it out on top. Fill the filter with water, then put the multiport valve back on and connect the plumbing. Place the multiport valve in the rinse position and rinse the sand on high speed til the water runs clear. Turn off the pump and put the multiport in the filter position on low pump speed. When the pump is on low speed it may only register 1lb of pressure with a clean filter. When you run the pump on high speed you should see higher pressure in the filter.
 

btpoole

Member
Jun 1, 2012
12
Thanks for the suggestions. I removed all the sand, not fun, re-positioned the stand and laterals. Refilled the filter and replaced the value. It seems to be working better, I'm getting the typical flow on backwash accustomed to and the water actually looks like it has discoloration and debris. The gauge did move some, still lower than I expect but some movement. Flow back into the pool on filter and recirculate is still good. Got small leak now on input union going into filter but I think I can fix that. Thanks again for the help.
 
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