Lack of Flow From Returns

[bgray9]

Hi,

In recent weeks I've had trouble with weak flow from the returns. I took apart the DE filter and hosed all the insides off a few weeks ago. For the last couple years I've been using the wood fiber substitute instead of DE powder, as I didn't like the DE powder building up in the yard when I backwash. I keep the skimmer and the leaf catcher and the basket at the pump cleaned out regularly. The strange thing is if I run the backwash, even for just a few moments, I get real good flow for maybe a day or so (and lower pressure reading on the DE filter) and then it drops off again, with the pressure reading on the DE filter bumping up to close to the level when I'd backwash again. Also, the last couple times I backwashed, I didn't get much dirty water coming out, and we haven't had much weather that would get much dirt or anything in the pool to clog up the DE filter. The last time I backwashed I didn't put any new fiber in and the water flow still drops off after a day or so. I checked the impeller and there was a little bit of stuff there that I cleaned out. I'm at a loss as to what this could be. I may just take apart the DE filter again just to check everything inside again. But I'm puzzled how I get good flow for a day or so and then it drops off again when there really isn't much in the DE filter itself that would be impeding flow, as far as I know. Any advice, ideas, etc. would be much appreciated. Thanks.

 

[mknauss]

Have you done a Overnight Chlorine Loss Test to check for algae? Sounds suspiciously like an algae bloom.

 

[bgray9]

No, I haven't. The pool water quality has been very good. I had a day or two back a few months as the weather here was starting to warm up where I saw a little green in a couple spots in the pool, but I did some shock, etc. and haven't seen anything further or had trouble with the pool being out of whack.

I'll run one tonight/tomorrow.

 

[bgray9]

OK, I just ran the tests. Here are my results:
ph: 7.5
FC: 7.4 (higher than I usually have it, as I put in some extra earlier this evening to ensure I was high enough for the overnight test)
CC: 0.6
TA: 80
CH: 700
CYA: 40

I rarely have checked the CH level and that sounds a bit high. Could that level create any problems?

I'll test the chlorine readings again in the morning and post them.

Thanks.

 

[mknauss]

As your CH is getting high be sure to manage CSI with pH and TA to prevent scaling.

 

[bgray9]

So I just ran the chlorine test again. I did it three times, just to be sure of the results. The three tests came in at 5.2, 5.8, and 6.0. So that's a difference of between 1.4 and 2.2. So, from reading the overnight test page it says that anything over 1.0 indicates there's something going on and you need to slam the pool. Is it possible to have an algae bloom and have the pool itself looking crystal clear? Would the bloom possibly be hidden in the filter or something like that? Thanks.

 

[mknauss]

An algae bloom can be difficult to see with the naked eye at its nasceant stage. The water might just look a bit dull.

The filter is filled with pool water, so the conditions are the same in it as in the pool.

I suggest you SLAM. It should go quick.

 

[bgray9]

I'll plan to do the SLAM starting friday after work so I avoid on-peak electric rates over the weekend. The only SLAM result I don't currently have is passing the overnight test, so I'll plan to check that saturday night/sunday morning.

 

[bgray9]

SLAM is on-going. Still the same pattern of the returns flowing strong for a little while after doing a backwash (even for just 30 seconds or so) and then greatly slowing down again in a couple hours. I'll run the overnight test tonight. The pattern is quite predictable at this point. I still wonder if something isn't quite right inside the DE filter assembly. When I cleaned it out a few weeks ago I gave it a good hosing off, but I think I've read where at times people will do a more involved cleaning of the filter elements. Would that be something to look into and if so, what is the method for such a cleaning and would it work for the cellulose fiber media as it does for the DE media?

 

[mknauss]

DE filters can get clogged with calcium.

Search the forum for threads that dealt with that. Use the search box upper right on this page.

 

[bgray9]

So the overnight chlorine test came out good this morning. I've read on here that chlorine can cause the cellulose to start breaking down and turn into a gel like mess in the filter. I'm thinking I probably need to do a more thorough cleaning of the elements. I replaced the elements like 6 months ago, so would it be likely for calcium to build up in that short a timeframe?

 

[mknauss]

Never heard of the cellulose thing.

Water are your water chemistry test results?

- - - Updated - - -

I see you had some results posted.

Depending on how diligent you are at keeping your pH low, your CSI could be in scaling tendency which could cause calcium scaling in your filter.

 

[bgray9]

Cellulose is fine wood fiber and is an alternative to DE. There are some discussions of it on the board here and there. It doesn't give a buildup in your yard from backwashing like DE does, which is a big deal for me with kids playing in the yard regularly. But cellulose doesn't backwash very well so you end up taking apart your filter and cleaning more often. Our filter is pretty old and has a few issues from the drain being hard to keep from leaking of you open it, to the metal belt around the middle being hard to get tightened properly so it doesn't leak after each time I take it apart. I'm thinking of either going back to DE for at least the short term or maybe switching to a cartridge filter setup. The cellulose is great in certain ways, but a real hassle in having to break down the filter and clean it so often.

 

[ajw22]

I tried cellulose in my DE filter for a season and went back to DE. You should try going back to DE and see if your problem goes away. If so you can then decide if you stay with DE or change to a cartridge filter.

 

[bgray9]

For a cartridge filter, given that we have a 1 HP pump, is there a size limit based on the pump? I've generally read that you would want to size the filter as large as possible to reduce how often you clean, have more cleaning surface, etc. But I didn't know if I got, say, a large 420 or 520 sq. ft. cartridge filter whether the pump would be big enough?

 

[ajw22]

For a cartridge filter, given that we have a 1 HP pump, is there a size limit based on the pump? I've generally read that you would want to size the filter as large as possible to reduce how often you clean, have more cleaning surface, etc. But I didn't know if I got, say, a large 420 or 520 sq. ft. cartridge filter whether the pump would be big enough?

Too small of a filter for the pump HP can be a problem.

I dont think a larger filter for your pump HP is an issue.

 

[bgray9]

Never heard of the cellulose thing.

Water are your water chemistry test results?

- - - Updated - - -

I see you had some results posted.

Depending on how diligent you are at keeping your pH low, your CSI could be in scaling tendency which could cause calcium scaling in your filter.

If there is calcium scaling, is it something that is visible? And how is it treated?

 

[bgray9]

So I opened up the filter this morning. The elements were dirty, but not terribly. They had a bit of a green hue to them, the kind of aqua green similar to like when copper is rusting. So I hosed them off and will soak them now with dish soap for the morning.

The little hose with the mesh cap on top, I think it's called the air bleed, was caked over, which I've noticed has happened regularly for years and I haven't found a way to stop it from happening.

 

[mknauss]

Sounds like no calcium. That is good.

Do you use copper containing products in your pool? Is your Ionizer adding copper?

You really do not want to add copper to your pool. At some point it will start to stain the plaster. It will also turn blonde hair green.

 

[bgray9]

I've never seen the copper rust colored stuff in the filter before. The filter is back together and I'm running it for awhile without adding DE, just as a test, as before it would always start slowing down in an hour or two. I really think it was the cellulose stuff that just wouldn't come off when backwashing. In a couple hours I'll add DE and then let it run through the evening, monitoring it.

We've used the ionizer for 6 years or so and never had trouble with hair turning color or staining. My father-in-law, who introduced me to them, has used an ionizer for close to 20 years. I really like that I can used a lot less chemicals in the pool, as I have small kids swimming in them. If we had issues with staining or hair turning green or something like that, I'd definitely have to reconsider. Our ionizer element is a combination of copper and zinc alloy.