Mountain range in Sand Filter?

[deadrabbit]

This year was supposed to be a great pool year. I replaced my pressure gauge, sand, multiport plunger/gasket, and o-rings at the beginning of the season.

I ran the system for three weeks (never backwashed) and found the pressure would not increase. So, I felt forced to backwash anyway. I don’t want to backwash if I don’t have to in order to retain chemicals/increase filtering ability. I was thinking that maybe my pool was just too clean, if that’s possible. If there was dirt in the pool after a storm I could vacuum while filtering and the filter would catch every piece without returning anything. I checked this using stockings. I checked the function of the new pressure gauge by switching from filter to recirculation or changing inlet or skimmer orientation. All seems well. I get a 3psi change from recirculation to filter. So then I thought my pool was just too clean and I would add D.E. in order to test the pressure and catch very small particles.

I added ½ a cup at a time until I was up to eight cups and still didn’t have a pressure increase!! I immediately pulled the multiport to see what was going on and the top of the sand looked like a mountain range. There were large valleys and peaks. The DE was stuck in the valleys or any level surface.
[attachment=1:sbav76tu]Picture1.jpg[/attachment:sbav76tu]

I backwashed the filter and took it apart. The sand was nice and level.
I rinsed the filter and took it apart. The sand was nice and level.
I filtered for 20 minutes and took it apart. The sand was nice and level.

I added 4cups of DE without a pressure change. Took apart the filter and found the sand was nice and level and was covered in DE.
[attachment=0:sbav76tu]Picture2.jpg[/attachment:sbav76tu]

I let the system run for an hour and also vacuumed some dirt. Took the filter apart and found the sand was level, covered in DE, and the DE was covered in the dirt. But, still no pressure change.

What is going on?? Why won’t the pressure increase? I don’t think it’s channeled because it retains any dirt or DE I put into it. The pressure gauge seems to be working. Where did the mountain range come from? The pool looks better than it ever has. I will take it back apart tomorrow to see if the mountain range develops over time.

Thanks in advance

 

[Dale.s]

I also get no pressue increase from clean to dirty but the flow at the returns does drop to hardly anything when I need to backwash, I sure do wish the pressure would increase and the filter got full though, sure would make it easier to tell when it's backwash time!

 

[zea3]

Deadrabbit- I don't know what caused the mountain range, but if your water has been clear you may not have collected enough dirt to cause a pressure rise. If you are still getting good flow from the returns then everything should be fine. If the return flow is decreasing then your new pressure gauge may be defective.

Dale.s- You probably need a new pressure gauge. They are relatively cheap and easy to replace.

 

[Bama Rambler]

It takes a long time for mine to ever show a pressure increase. And then it appears to happen all of a sudden. There's a lot of sand in there to hold stuff so it takes quite a while with a clean pool for it to plug up enough to see a pressure rise.

 

[deadrabbit]

Installed a new pressure gauge with no change. I removed the multiport after allowing it to run for the last couple days and I have a new mountain range. I also have some D.E. in the pool. I think I’m going to backwash the D.E. and run only sand like I have been. It has always worked and the D.E. was just for fun. It’s sort of disappointing because I had heard so many good things about adding D.E. The only thing that would make sense to me is if my pump were too big. As long as the pool stays clear like it has been, I’m not too worried.

 

[JohnT]

We have the exact same filter and pump. Mine seldom shows a small pressure increase. Seems like it jumps from normal to high in a very short time.

 

[Melt In The Sun]

I'm not real familiar with sand filters, but it seems like if you have water swirling around inside at a decent speed, it would form dunes that look like your first picture. I don't know if that's possible, but your first picture sure looks like what would result from that.

 

[deadrabbit]

if you have water swirling around inside at a decent speed, it would form dunes that look like your first picture.

What would cause the water to swirl? Channeling?

Could an incorrect sand type (not silica #20) cause swirling or channeling?

I think I may change my sand again. I used PaveStone sand from Home Depot because it was half the price of other products. The reason I might change the sand again is because nowhere on the bag did it say anything about the silica size. I just assumed that it was silica #20. It may be, but it doesn’t say so on the bag. Also, Home Depot advertises the bags at 50lbs but I weighed them and they all weighed 40lbs each. I called Pavestone for product information and they told me to call Home Depot. Who knows? Maybe there is a difference between sand quality. Or maybe Pavestone sand is not silica #20.

I would like to use the D.E. because now I have 25lbs of it and no use for it!

 

[JasonLion]

I really doubt that PaveStone sand is appropriate. Pool filter sand has an especially fine/small and uniform grain size. Paver sand is normally designed with a wide variety of grain sizes to help it bind with the pavers into a solid mass, and normally avoids including fine grained sand because it can wash out too easily.

 

[deadrabbit]

I really doubt that PaveStone sand is appropriate. Pool filter sand has an especially fine/small and uniform grain size. Paver sand is normally designed with a wide variety of grain sizes to help it bind with the pavers into a solid mass, and normally avoids including fine grained sand because it can wash out too easily.

PaveStone makes a sand for pool filters. It is sold in the pool section at Home Depot. http://www.homedepot.com/Bath-Outdoor-H ... ogId=10053 It says Pool Filter sand all over the bag but does not say silica size. I thought about it for hours but the price was just too good. Guess I will learn something from this. The only thing that made me think "OK, this must be filter sand" is that the back of the bag had a warning label about silica. Therefore, I assumed it was silica 20. I think my best bet will be replacing it anyway.

 

[JasonLion]

Interesting, I didn't know they also made pool filter sand. If it is labeled for pool filter use, it should be fine. All of the pool sand filters use the same kind of sand. Paver sand will not work.

 

[stephentx7]

Interesting read here. I was just about to make a post asking if anyone has used Home Depot's - Pavestone Pool Filter Sand and had any problems. Pavestone is the company. They make a lot of various sands/rocks/pavers/etc... This is clearly marketed as POOL FILTER SAND...not as Paver sand etc...

Last year I replaced the sand in my filter and purchased it from a local Pool Store and it was a white sand in brown bags. I also hired someone to do the sand change for me.

Well I am just now finishing what I considered to be a fairly painless Baqua conversion and I need to change my sand again (from what everyone says). Well doing the research I have found that Home Depot carries this sand (marketed as Pool Filter Sand) for $5.95 a 50lb. bag. That's nearly half if not more than half of what other stores are quoting me. The red flag for me was the sand is a tan color...and I remembered the sand I purchased last year being white.

Now I don't know what to do. After all...money is money...and I would rather not have to do this more than once.

 

[deadrabbit]

If you decide to go with the Pavestone sand from Home Depot, remember to weigh it. All the bags I bought were advertised at $5.95 per 50lb bag but were only 40lbs a piece. I used two different scales to make sure. This changes the price to about $7.44 per 50lbs!!

 

[stephentx7]

If you decide to go with the Pavestone sand from Home Depot, remember to weigh it. All the bags I bought were advertised at $5.95 per 50lb bag but were only 40lbs a piece. I used two different scales to make sure. This changes the price to about $7.44 per 50lbs!!

You know what else is weird? On Home Depot's website under the "Specifications" tab it says "Size: 50 lbs." and if you go up a little it says "Assembled Weight: 46 lbs." And at the store...it doesn't give a weight on the bag...it just says ".5 Cu. Ft."

I was even going to call Pavestone directly to ask about the Silica grading issue you called them about. It doesn't say anything on the bag.

I dunno...I am all about saving a few bucks...but peace of mind can be priceless...I guess I'll call the Pool Store and just be safe.