Trouble filtering out dirt

[t00manyusers]

Hi all,

I'm having a very strange issue. My filter seems to not be filtering dirt. Here's what happens: when I vacuum in "filter" mode, the jets tend to return cloudy water back (which tends to contain most of the fine dirt I'm picking up with the vacuum). If I vacuum to waste and a section of the pool becomes very clear, then switch to Filter and continue vacuuming, the water immediately dirties up.

I spent a good hour on the phone with Dave, who is a completely awesome guy (I called in about the test kit, and we ended up chatting about my pool problem) and he ended up striking out, so maybe someone out there can recommend something.

Here's what I tried:

- replaced sand
- verified laterals are not broken in the process
- disassembled Vari-Flo multi port valve, no damage. Seals seem "okay" for what little I know about them.
- piping seems okay, when pump runs, no air comes in

I'm stumped. I'm also dealing with a huge algae problem but I can't even vacuum the **** things because they just get returned to the pool

Any help welcome. Thanks!

 

[jblizzle]

Welcome to TFP!!!

Please add your pool details to your signature as described HERE as it will help us help you.

How big is the sand filter? How big is your pump?

As I am sure Dave told you, algae is not a filter problem it is a chemistry problem. Once the chemistry is taken care of, then the filtering becomes more important.

 

[t00manyusers]

Welcome to TFP!!!

Please add your pool details to your signature as described HERE as it will help us help you.

How big is the sand filter? How big is your pump?

As I am sure Dave told you, algae is not a filter problem it is a chemistry problem. Once the chemistry is taken care of, then the filtering becomes more important.

Err I did add a signature - maybe it's not posting because I'm on my phone. I'll see if I can revive it. 300lb Hayward S-244T and a 1.5hp (SF 1) pump, 1.5" piping. Agree it's chemistry but not concerned with that for now - can't figure out why stuff returns. Once my test kit comes in next week, I will do the SLAM - but if all of it returns right back to the pool, that will hardly help... so have to figure that one out first

 

[bobodaclown]

If your chemistry is off, (not enough chlorine to kill the algae), it continues to grow, when you turn the pump on, what has grown in the filter and piping gets return to the pool.
If it's actual dirt/sand then it might be a cracked lateral. You could use an old white sock or nylon try catching some of the stuff at a return and inspect it closer.

 

[t00manyusers]

If your chemistry is off, (not enough chlorine to kill the algae), it continues to grow, when you turn the pump on, what has grown in the filter and piping gets return to the pool.
If it's actual dirt/sand then it might be a cracked lateral. You could use an old white sock or nylon try catching some of the stuff at a return and inspect it closer.

Hmm. As part of my sand replacement, I examined the laterals VERY closely - I even took them to a pool store to explore, and I'm sure they'd have happily sold me a new set if they were even remotely bad. But they were great; I cleaned some grains of sand from them and put them back in.

I see what you mean about the stuff in the pipes returning, but what I mean is this: when I vacuum, it RAPIDLY returns. It wouldn't be something already in the pipes as it's directly proportionate to the amount of dirt going in the filter. That is to say, if I manage to get the section next to the jets somewhat clean, and begin vacuuming with the multi port set to Filter, almost right away a noticeable dirt cloud begins to form.

 

[mickey4paws]

I'm confused. Shouldn't you want to be vacuuming to waste, and not in filter mode?

 

[t00manyusers]

I'm confused. Shouldn't you want to be vacuuming to waste, and not in filter mode?

Well... I've always done that when the pool is extremely dirty (partially because in the three years of pool ownership, I don't think I was ever able to vacuum to 'Filter', as it would tend to always come back). However, speaking with Dave, he feels it's a huge waste of water and isn't the way that pool filters are designed - they ARE designed to trap anything visible - and also considering we pay for water here, it does seem a bit of a waste.

The other problem is, I don't mind vacuuming sediment off the floor to waste, but whatever is *floating* in the water seems to get returned as well, right? So if I manage to kill all the algae using chemistry, they will just come right back, won't they?

 

[achianese]

I see what you mean about the stuff in the pipes returning, but what I mean is this: when I vacuum, it RAPIDLY returns.

Certainly focus on getting the chemistry under control as well, but it does sound like your filter is probably returning material that has just entered it based on this description.

I'm a new pool owner this year, so I don't have a lot of experience, but the story of my pool opening earlier this year is kind of similar to what you're experiencing. I have a 19K gallon pool and the exact same sand filter. When I opened in the spring and did the initial SLAM, my water was very cloudy with dust and dead algae. My filter was not removing the fine particles very efficiently, and this was evident in the long time it took to clear the water. Also, when vacuuming I saw essentially what you have seen: cloudy water came back out of the returns. I think this is just the nature of a sand filter: it isn't very efficient at filtering out very small particles very quickly. This is especially true right after a backwash and might be true with new sand as well. I bought a little bag of DE and experimented with adding some to my filter as described here:

http://www.troublefreepool.com/content/133-add-de-to-a-sand-filter

What happens is the one cup or so of DE forms a fine layer on top of the sand that catches the small particles. While this removes the cloudy stuff, it also got clogged up pretty quickly in my experience, so I was backwashing more than once a day to remove the cloudiness. This eventually worked to clear my pool in about a week of careful watching of the pump pressure, backwashing when it rose 25% or so, and adding fresh DE to the filter.

For the past two months or so, my pool has been perfectly clear, I haven't backwashed, and I haven't added any DE to the filter. Again, this is just my own experience and I'm not sure how much the DE really helped clear my pool, but it's something to read up on anyway, and maybe others have an opinion on this.

 

[t00manyusers]

Certainly focus on getting the chemistry under control as well, but it does sound like your filter is probably returning material that has just entered it based on this description.

I'm a new pool owner this year, so I don't have a lot of experience, but the story of my pool opening earlier this year is kind of similar to what you're experiencing. I have a 19K gallon pool and the exact same sand filter. When I opened in the spring and did the initial SLAM, my water was very cloudy with dust and dead algae. My filter was not removing the fine particles very efficiently, and this was evident in the long time it took to clear the water. Also, when vacuuming I saw essentially what you have seen: cloudy water came back out of the returns. I think this is just the nature of a sand filter: it isn't very efficient at filtering out very small particles very quickly. This is especially true right after a backwash and might be true with new sand as well. I bought a little bag of DE and experimented with adding some to my filter as described here:

http://www.troublefreepool.com/content/133-add-de-to-a-sand-filter

What happens is the one cup or so of DE forms a fine layer on top of the sand that catches the small particles. While this removes the cloudy stuff, it also got clogged up pretty quickly in my experience, so I was backwashing more than once a day to remove the cloudiness. This eventually worked to clear my pool in about a week of careful watching of the pump pressure, backwashing when it rose 25% or so, and adding fresh DE to the filter.

For the past two months or so, my pool has been perfectly clear, I haven't backwashed, and I haven't added any DE to the filter. Again, this is just my own experience and I'm not sure how much the DE really helped clear my pool, but it's something to read up on anyway, and maybe others have an opinion on this.

Interesting. I will investigate this. Maybe I will try adding some ... maybe it will help. We have about 4 days of nice weather ahead so I was hoping to at least clear up the pool to use it, even if I might not get the chemistry quite right until I get Dave's kit on Monday...

 

[Abigail K]

Before you try adding DE to your filter, I would suggest you try doing a deep clean of your sand filter first.
Adding DE to a sand filter is generally recommended towards the end of the SLAM process rather than the beginning.

 

[t00manyusers]

Before you try adding DE to your filter, I would suggest you try doing a deep clean of your sand filter first.
Adding DE to a sand filter is generally recommended towards the end of the SLAM process rather than the beginning.

My sand is completely clean ... seeing as it's about two weeks old at this point.

I'll hang on with the DE until I get my kit and start the SLAM process, I guess. I just hope it helps - cause if it doesn't, I have no idea what to do anymore.

 

[one_knight4u]

The average human can see down to 0.1 millimeter (10 microns) and the specs for a sand filter are "down to 20 microns". Ill step out on a limb and suggest that maybe your filter is working perfectly but there are just alot of smaller particles that are getting through.
As others have suggested, adding some DE to your filter should tighten its filter capabilities to a point of it catching the smaller particles. When I added DE to my skimmer, I could see a white stream coming from the jets. I used my vac hose to cover the return jet and put the other end of the hose in the skimmer to circulate the second addition of DE in a closed loop until it "stuck" in the sand filter. I left the hose in place less than 5 minutes.
I would agree with Abigail and wait until you have finished your SLAM.
One last point to note, as a filter starts to get plugged up, the size of debris it catches will be smaller, but because you have a situation that is unique, might i suggest that you let your pressure go a little above the recommended 25% backwash settings and stretch that out to 35% to trap the smaller particles.
I know it is outside of the realm of what is practiced here but like i said your situation seems to be out of the norm. and sometimes techniques have to be tweaked to fit individual needs.

 

[mas985]

There are species of algae that when dead can easily pass right through a sand filter so if you did have algae at one point, it is quite possible that the dead algae just keeps getting recirculated. DE should help.