Fine layer of reoccurring dirt/DE

[Sonny12687]

Want to provide as many details here as I can, I appreciate any help in advance -

I recently moved into a house with a 20,000 gallon in ground salt water pool with a spa spillover/waterfall with a DE filter. I am having an issue with a very fine layer of dirt (for lack of a better word) on the pool floor. When running a brush along the bottom of the pool, the dirt would kick up and the pool water would become extremely cloudy. The next day, I tried vacuuming it, only to have it return again the next day. A few days ago, I completely cleaned the DE filter and recharged with DE. I checked, and did not notice any issue with the grids, manifold, or pipe itself. The dirt continued to return the next day. I then checked the spider gasket in the multiport valve, it was in awful shape. I ordered a new one and replaced it. At this time, I also added clarifier. Then, I vacuumed up the dirt again. The next day, the issue was improved considerably - no dirt building up while filter was running. However, today, I am still having a very fine layer of dirt on the bottom of the pool but also some in the spa section. I tried brushing it and while I can see the cloud kick up, the pool doesn't become nearly as cloudy as it initially did, even when brushing the whole pool bottom.

Some initial thoughts and notes I have -
-could this be DE returning to the pool? If so, where could it be coming from? I know I added the correct amount after cleaning, and I don't want to add too much.
-the only "red flag" I noticed when cleaning the pool filter was the manifold didn't sit on the standpipe as tightly as I thought it would have. When pressing it manifold down onto the standpipe, it slides back up a little bit. The standpipe O-ring seemed to be intact. Is the Oring supposed to be inside of the pipe on the manifold? Or is it supposed to be on the outside of it on the standpipe?
-pool water chemicals and salt are in balance
-all Orings and gaskets were lubed up with Magic Lube

Thanks again in advance!

 

[duraleigh]

Welcome to the forum
Roughly 80-90 percent of the time when folks report recurring "dirt", it is dead algae.

That means the first thing we would need is a current, complete set of test results......can you supply those?

 

[Rocco]

If you are not sure if it is dirt or something returning to the pool I recommend getting a bucket of water and putting on the deck next to the pool.

The next day if the bucket also has dirt in the bottom you know it is not an issue with your filter.

However based on your post it appears that something is bypassing the filter or dead algea as duraleigh suggested.

Do you feel confident that the multi-port valve is in good shape and is fully in the down position creating a seal against the spider gasket?

 

[Sonny12687]

Welcome to the forum
Roughly 80-90 percent of the time when folks report recurring "dirt", it is dead algae.

That means the first thing we would need is a current, complete set of test results......can you supply those?

If it is in fact dead algae, shouldn't it still go away after vacuuming up? Or are you suggesting each day, more algae is dying and I'm just seeing new dead algae?

As for test results, I have only test strips on hand, will that suffice?

 

[duraleigh]

Or are you suggesting each day, more algae is dying and I'm just seeing new dead algae?

Yes. That is normally the case. If you decide you want to follow what we teach here on TFP, the strips will not be adequate.

Please read "The "ABC's of Pool Water Chemistry" up in Pool School. That'll give you a "taste" of what we do and you may like what you read. The recurring dead algae can be removed by a SLAM so read that procedure, too.........you will need either a Taylor 2006C or a TFTestkits TF-100 to perform the precision testing that is required for pool water management.

Both are under $80.00 but there is no possibility that strips will be adequate.

 

[Sonny12687]

TC - 8.0ppm
FC - 8.0ppm
PH - 8.0
Acid demand - 2
Alkalinity - 119ppm
Hardness - 300ppm
Stabilizer - 20ppm
Dissolved Solids - 5,000 ppm
Salt - 3,100

Test was done by local pool store yesterday. They provided me with muriatic acid and stabilizer to correct the PH and stabilizer levels. Yesterday, the "dirt" did return as well as this morning (been vacuuming it up every morning.)

 

[Oly]

Beware of "free" pool store testing, it often winds up costing you quite a bit. If you are serious about managing your pool chemistry, purchase and learn to use a good test kit.

For example you will need to perform an overnight Free Chlorine loss test to determine if you have an algae problem. Read about it here....Pool School - Perform the Overnight FC Loss Test (OCLT)

To fully understand your water chemistry you need frequent and precise testing and that involves doing it properly yourself with a real test kit you own and maintain.

First determine if you have algae. If you simply have dirt or somehow have excess DE then you should be able to remove it with a robot cleaner or by vacuuming to waste. If it is DE and it is returning after the filter runs then you have filter grid or gasket issues.

 

[Sonny12687]

I'm pretty certain at this point that it is DE returning to the pool. Yesterday I took the filter apart again and cleaned. There was DE all over the top of the manifold and sitting on top of the grids (picture attached). It looked as though there was only some DE on the top half of the grids and almost none on the bottom half of the grids. The bottom halves looked freshly cleaned in fact. I took apart all of the grids one by one and inspected, as well as inspected the top and bottom of the manifold. Still no cracks or tears anywhere. I have been vacuuming these little piles of DE every single morning only to have them return the next day. They show up consistently in the spa of the pool (spa is above pool water level) and some can be found in the deep end of the pool near the drains.

Question - the valve at the top of the manifold, when should water be coming out of that, if at all? I.e. - what is it's purpose?
I have had a thick layer of DE built up around that each time I've cleaned it for this issue.

 

[Sonny12687]

For anyone interested or any others that may be having a similar issue - I have resolved the issue with the DE returning to the pool. After browsing some other forums, I was pointed in the direction of removing and checking the internal air bleeder (as shown in picture above). There was a small separation on the underside of that where it connects into the manifold. It looks as though the clamp that was on there was not stock and a band aid fix put there by the previous owner. I replaced it with a new (and updated) part from Pentair and I am now on 2 days without DE returning to pool.

 

[Oly]

Thanks for the update. Did you replace the manifold? If so how was it modified?

Happy you solved the problem.

 

[Sonny12687]

The manifold was not replaced. In the above picture, you can see the worm gear clamp on the inner air bleeder. I, of course not knowing any better, assumed that was stock and supposed to be on there to connect it. The inner air bleeder on this slides in and out of the connection to the manifold. I removed it, and noticed there was a preexisting (from before I moved in) crack on the underside. The previous owner added duct tape underneath and then the gear clamp. Once I saw the duct tape I knew it wasn't as designed. So I ordered a replacement/updated part (Amazon.com: Pentair 190092 Internal Air Bleed Assembly Replacement FNS Plus Pool and Spa Vertical Grid D.E. Filter: Garden Outdoor ) . The new part connected perfectly and the next two (now three) days later there hasn't been any DE on the bottom of the pool.