Filter Issues

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
I’ve been trouble shooting various, umm anomalies, with my pool over the last couple weeks. Basically, it all revolves around recurrent ‘dirt’ on the bottom of the pool that shows up after running the filter.

Sunday I unscrewed the return eyeballs and put pantyhose over the returns. That night I collected a fair amount of debris in the pantyhose- mostly Crepe Myrtle blossoms, and Zeosand. Floor of the pool remained clean this night. I’m pretty sure the Zeosand is what I’m seeing and thinking is dirt- it was a pretty dark grey when wet.

Realizing channeling is a good possibility, and having read here about tapping the sand filter to jar the sand I proceeded to tap the side of the filter. I diligently watched the pressure gauge for any sign of a change- none. Turned around and saw clouds of opaque white ‘something’ blowing into the pool from all 4 jets. The pantyhose were still on the jets and this material was small enough to go right though. Watching in stunned disbelief I finally made it back to the filter to tap some more- and watch more clouds of white debris blow into the pool.

I backwashed thoroughly on Sunday afternoon- 2 backwash & 2 rinse cycles. I exclusively manually vacuum to waste- the last time being Sunday before backwashing.

I have a top mount Hayward Sand filter- without unions- and will need to cut plumbing to access the sand (Zeo 3-4 years old) so although it’s not out of the question I’d like to try some less invasive troubleshooting first. Not to mention that it’s 8,276 degrees outside and the thought of removing all that sand right now… What about the spider gasket- any chance I could be that lucky? Any other thoughts?
 

Lawrosa

Active member
May 19, 2010
44
Central NJ
Question: I backwashed and now the Zeobrite is spitting out into my pool. What should I do?

Answer: If the Zeobrite granules are actually returning to the pool, this is an indication of a mechanical problem. The most likely source is a cracked or loose lateral. When you change your filtration media you should always inspect these laterals very thoroughly. Look for cracks in the solid portion of the lateral or broken slits that can cause media to escape. Although these cracks are very difficult to see, once the filter is running under pressure, it will cause the cracks to open, and the filter media can be blown back into the pool.
Another cause of this situation could be the spider gasket in the multiport valve. If this gasket gets pinched, cracked, or broken, it can allow media to bypass during backwashing and collect in the return pipe. When the filter cycle is started, the material in the return pipe will be blown into the pool.
A third cause could possibly be the air vent tube not being properly installed. Not all filters have an air vent tube, but for those filters that do, it is there to relieve any air buildup in the filter and expell it through the return pipe. If this tube is allowed to lay on the media bed, it can siphon granules into the return pipe.
 

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
Thanks for the info on cleaning the filter. I haven't done that. Looks like I can clean without opening the filter, if I can solve the debris in the pool issue I will probably wait for fall (or a less hot front :mrgreen: ) to regenerate. Wonder, though, if those ammonium ions could be responsible for my mysteriously disappearing cya...

I'm going to replace the spider gasket. It was still seated, and not torn/ missing any parts, but it has seen better days. Interestingly, it is the worst looking on either side of the backwash port. Could this be indicative of a problem with the valve? I read a post by Jason (?) that discussed shaft seals and spring issues- would either of these result in more pressure on one side of the valve?

I've been told many things over the years regarding this gasket- glue in/don't, lube/ don't, always turn same way, doesn't matter, etc. What is the general concensus here? I'm going to try super glue this time- can I then put the valve back together right away (versus the dry time needed for silicone)? And I have some pool/spa lube from Leslie's. Do you all periodically open the valve and re-lube this gasket? What is the life expectancy of a spider gasket?

Good news is that I collected noticeably less debris in the pantyhose over the return jets last night, and very little zeosand. Maybe that's an indicator that the problem is occuring when I have it on waste, backwash, or rinse.

I suppose this still doesn't address the cloudy water blowing into the pool when I tapped the filter, though. :( Maybe the cleaning will help that.
 

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
Replaced the spider gasket and lubed it with the pool/spa lube. How freely do most MPVs move? Mine sure feels like it's binding on the gasket when I turn it. I am pushing down on the handle before turning.

In fact, once I installed the gasket and put everything back together I spun the valve around and felt enough drag I thought I had pulled the gasket loose. I opened it back up and the gasket was seated fine, so I decided maybe I was tightening the screws too tight and left them looser this time. Ended up having to tighten them though as water spit out when I turned the filter on.

So, how freely does your Hayward MPV move, does it glide smoothly or can you feel it binding/dragging on the gasket?
 

Lawrosa

Active member
May 19, 2010
44
Central NJ
Get a new washer for under the handle. Take the pin out of the handle when the valve is apart take out the shaft and spring and lube the shaft and O rings. Mine is like butter now.
 

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
Thanks Lawrosa, this must be what I need to do. Been looking for a schematic online so I can see what parts are inside there, but no luck so far. Butter, huh- as in it spins that easy?
 

Lawrosa

Active member
May 19, 2010
44
Central NJ
You could just find your model # and just buy the top half of the MPV. They are only $20-30 bucks I think. Look on the top of valve. should be a #714. Most popular. This way you dont need to mess with it.
 

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
Gave in and removed the Zeosand from my filter this evening. I found a crack in the center pipe, up near the top, and I suspect this is where the debris (mostly crepe myrtle blossoms) was getting into the return lines.

A cursory look at the lateral lines shows them to be intact, I’ll have to clean them up to inspect better, but is it normal for the sand to be imbedded in the grooves like this? There is quite a bit of sand inside the laterals as well as the hub, too.
 

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Lawrosa

Active member
May 19, 2010
44
Central NJ
I think its normal for the sand to be in the laterals like that. As far as the center pipe thats cracked that would be your issue with sand and dirt getting back in the pool. I had to buy the whole tube and laterals as a complete set. 60 bucks at the pool store. With new sand was 100 bucks with tax. I went with the middle of the grade sand. The pool store actually told me not to go with Zeobrite. Too much maintanace. Middle grade sand was 12 bucks a bag. Has a white color.
 

Terry

Well-known member
Jul 8, 2008
128
Dallas, Tx
If you can believe it, there is apparently no store in the DFW area that stocks this part; 7-10 business days for the pool store to order it in. I've been considering replacing the filter, but had a death in the family and need to put it back together and leave town.

The crack in the center pipe is just in the top 3", laterals all look good. Plumbing shop suggested using a Fernco coupling over the cracked area to prevent it from opening up. The coupling covers the crack by a couple inches and goes up to where the mpv sits over the pipe.

I plan to use pea gravel as the base, then regular pool sand. Contemplating re-using some of the zeo in the top few inches. I already have it and maybe I can get some of its touted water polishing. Cross your fingers for me. :wink: