Sand filter problem

[Sunsoakin]

Hey guys, I'm new here and I have a problem with my filter.

I have an above ground pool 18' x 4' using a sand filter (hayward sm1700t) and a index saltwater pump. My backwash works fine, however, when set to "filtration" my sand pump will seize up after ten seconds or so (sand pump actually swells a little). I know it's not the motor because it runs fine on "backwash" and "rinse".

I never had this problem until I recently converted to saltwater. We disassembled the sand filter the first time this happened and checked the folding fingers that rest at the bottom of the filter for clogs. We thought maybe the salt hadn't completely dissolved yet. After we reassembled the filter the next day, perfection!

Everything worked fine until a week or so later when I noticed the return wasn't flowing as fast as you usually does. I thought a backwash would help but after turning in back to filtration it seized up again. Could it be that I don't have enough sand?

Sorry for the long winded story but I want to give as much detail as possible. Any suggestions are greatly appreciated!

 

[linen]

Welcome to tfp, Sunsoakin

Could it be that I don't have enough sand?

That shouldn't cause blockage, so I don't think that has anything to do with the problem.

I don't quite understand your setup. Do you have an intex combo pump/filter/swg that feeds into the Hayward sand filter?

What part is "swelling"?

What is your filter pressure when swelling and when working correctly?

 

[BadOleRoss]

If the sand tank swells up is sounds like the return line to the pool might be blocked.

 

[Sunsoakin]

Thanks for the welcome linen.

No what I have is an Hayward sand filter (http://www.hayward-pool.com/pdf/manuals/Manual144.pdf) running the water to my Intex 54601EG Krystal Clear Saltwater System (http://www.intexcorp.com/index.php/54601eg.html), which then runs into my pool. The swelling is happening to the tank that holds the sand. I'm beginning to wonder if I should have the saltwater system before the sand filter. When running normally the presser sits around 20 but jumps to 28-30 when it seizes.

Again all suggestions are gratefully appreciated. Thank you guys.

 

[Sunsoakin]

BadOleRoss

I'm not sure what could be causing the blockage as we've taken the pump apart twice now and every time I have to plug-up the intake and return so water doesn't flow out of the pool onto the ground. We disconnected the hoses at the sand filter not at the intake or return. Unless you are talking about a blockage inside the head of the sand filter. We've unscrewed the top and looked at the spring to get a better understanding of how the filter works and again everything looks fine...

 

[JohnT]

The blockage is going to be either in the filter or the line to the pool return.

Has the system worked before, or is this a new installation? What happens when you run with the filter valve set to recirculate?

 

[Sunsoakin]

Hey Johnt,

It is not a new pump but a new setup for me because I inherited the filter from a family member. It ran all of last summer when I was still using chlorine. It worked for a little more than a week with the saltwater system after we disassembled it the first time.

I have not tried to set it to recirculate. I will get on that ASAP!

 

[Bama Rambler]

There has to be something blocking the flow back to the pool. When you say the pressure jumps to 28-30 psi, is it all of a sudden?

It could be something loose in the filter or multiport that plugs off the outlet port after the pump starts and falls back down when you shut it off. Or it could be something in the plumbing doing the same thing.

 

[Sunsoakin]

Bama Rambler

Yeah it's all a sudden.

Johnt

I tried to recirculate at my lunch break...it seized up.

 

[Bama Rambler]

JohnT -- I tried to recirculate at my lunch break...it seized up.

That rules out the filter. Recirc bypasses the filter completely, so it has to be either something in the multiport or the return line.

 

[Sunsoakin]

My uncle has a spare multiport that will fit my tank. After work we are going to make the switch and see if that is the problem.

Just a question - What can go wrong with the multiport? It seems pretty basic being just a spring and channels.

 

[linen]

If you are getting no flow, then the ports in the filter/filter handle could be misaligned form when you took it apart...i.e. filter isn't filter, rinse isn't rinse etc.

 

[Sunsoakin]

We were careful to check the position of the ports when we took it off. When the handle is set to "filtration" there's an opening over two ports (one for the intake and one for the return) and we were sure to put it back that way. I will double check to make sure.

Could it be in the spring?

 

[Sunsoakin]

Ok, we've tried a different multiport from another pool that was working but when we attached it to mine the filter still seized up. We decided to run the filter without sand just to see if it would work and it still seized up. I can't find anything that claims my SM1700T won't work with saltwater either. We've checked the folding fingers for any blockage in the center tube and the fingers themselves...nothing.

We just removed the center pipe and finger completely and re connected everything without the guts and no seizing happened.

 

[linen]

The swg should have nothing to do with your problem.

Are you sure your standpipe is not blocked? It is the pipe that goes down from the valve to the fingers.

 

[Sunsoakin]

We just put everything back together without the sand again and everything is working fine. The sand is pretty new and I know it's No. 20 silica sand but should I try new sand anyway? Would a coarser sand work better? Maybe the sand is blocking the fingers?

 

[linen]

What brand of #20 sand are you using?

Do a long backwash to rinse out the small particles, at least 2 minutes. Then do a long rinse then back to filter.

Then switch to filter and note your pressure and post back.

 

[Sunsoakin]

I think the sand brand is HTC but I'm not 100% sure because the store is closed and they are a local company. I will find out tomorrow.

We put the sand back in the filter, ran a backwash for about 3 minutes, then a rinse for another 2. So far so good but I'm not sure if this will last.

Do you recommend any certain types of sand?

 

[Bama Rambler]

The only fault in your thinking it may be the sand is that it does it in recirc which bypasses the sand completely. If you changed the multiport then it had to be in the return line somewhere.

I think there was a blockage in the return line and it became dislodged during the work. You can put everything back together and I bet it will be fine.