2 speed pump question

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paulslund

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Jul 15, 2014
25
Ottawa, Ontario
I've been having some issues with my sand filter blowing dirty water back into the pool.. I've changed the sand and even bought a brand new multiport valve for it. Still does it. I'm convinced (but can't substantiate) that it's the "fancy" sand that my pool store sells (big chain store.. when I went to the local pool place they were closed so i had to get from the big chain).

I don't want to take a chance on changing sand again.. (just don't feel like doing it) so I've found a used cartridge filter that I plan on putting in line after the sand filter (I know..overkill.. why not just use the cartridge filter alone..). I figure the filter will last a lot longer if it's only catching what the sand filter is letting through.

But the guy is also selling with a 2 speed hayward Pro-LX pump (1.5hp). I wasn't going to use it but then thought of the energy savings.

So my question is: the low speed is only 1/6hp.. If I'm using low speed when not running through the solar panels will that still be strong enough to push through the two filters? Or should I just keep my 1.5 HP and use it normally. Will I get a full turnover at that low speed?

Just looking for insight. My interest was in the cartridge filter (and he's including a new filter) and then turned to the pump...

Thanks a lot!
Paul.
 
Adding two filters in series is a really bad idea. You will lose a lot energy efficiency and flow rate. You are better off choosing one or the other.

Let's focus on the sand filter. If dirt is blowing through the filter it can be one of two things. A broken lateral or very tiny dirt particles (dead algae). Did you recently clean up an algae bloom? If so, try a little DE in the filter to help trap the particles.

If it is a broken lateral, you can fix that by removing the sand.
 
mas985 said:
Adding two filters in series is a really bad idea. You will lose a lot energy efficiency and flow rate. You are better off choosing one or the other.

Let's focus on the sand filter. If dirt is blowing through the filter it can be one of two things. A broken lateral or very tiny dirt particles (dead algae). Did you recently clean up an algae bloom? If so, try a little DE in the filter to help trap the particles.

If it is a broken lateral, you can fix that by removing the sand.
Click to expand...

The issue with the sand filter has been going on for a number of years now. This spring I replaced the sand, removed, cleaned and inspected the laterals, and then replaced the multiport valve. From what I've been told if there was a cracked lateral I would see sand spewing out the return. I'm having an issue that if I turn off the pump, even for only 10 - 20 seconds to turn on the solar panel diverters (or off) and then turn it back on.. I get a flow of dirty water back into the pool.

I started to think that the pump was too strong for the filter..but the filter is rated at 42 (or 44) gpm and my research would indicate that 1.5inch fittings won't allow any greater flow than 42gpm (no matter how strong the pump). So I've been getting increasingly frustrated that I threw a bunch of money at it that doesn't seem to be working (although I think I needed the new multiport anyways.. the other one was getting really hard to turn and I think the spring was gone).

So I figured that a used, cheap cartridge filter (designed for a pool three times the size of mine) would catch the small stuff getting through and not overwork the filter as it's only catching the small stuff... But maybe that's not the best alternative.

I had thought of using DE or Cel Fiber but my concern is still there..when I turn on the filter won't it just blow some of the DE into the pool too...I don't know... Last year I had made a slime bag and the stuff it was catching was incredible.. and man the pool was crystal clear! I was hoping the new sand would fix that but no..it didn't...
 
my research would indicate that 1.5inch fittings won't allow any greater flow than 42gpm
Click to expand...
That is a recommendation, not hard limit. There is no limit to flow rate other than what a pump can produce.

But if the dirt is not algae, then it sounds like there is still something wrong with the filter. Did you check the multi-port filter for any damage?
 
The new one I bought? No I didn't.. but the symptoms were the same before and after the new multi-port was installed.

So then is it possible I"m pushing the water too hard through the filter? I have about 10 feet of flex hose feeding the 1.5hp pump. It definitely seems to be worse when the solar panels aren't running (that slows it down) but is still there (but I suppose that could be residual sitting in the stand pipe after being on without the panels? )

I think I'm going to start a new post regarding my problem..I've taken a video of what happens so people can see it, and I've taken a picture of the "sand" I got from the pool place (same stuff that was in it before, and what I put in when I replaced it). If I can get confirmation that the sand is the key then I'll go that route...just getting tired of throwing money at it you know?

Thanks!
 
You are better of sticking with the same thread. Mods like it better when you keep stuff together so there is a history of the discussion. However, you should be able to edit the title to attract more attention. If not ask the mod to change it.


But that pump is not really all the large compared to the filter so I don't think that is the issue. AG pumps are pretty weak (low head) by comparison.
 
So here's my story. I've been having trouble over the years getting the water crystal clear. I can get it clear but the way it should. Water chemistry is in check (although I'm still working on getting the alkalinity down as it's a smidge high at 120 give or take).

The filter and pump used to be under my deck, but I moved it last year as I was tired of crawling under there. That's when I really noticed the problem. I have the Zodiak SWG system and the salt cell is a clear rectangular tube. I happened to be watching it and noticed that when I turned the pump off, and then back on (say to turn off the solar panels, or whatever) it would shoot dirty water back into the pool! Now I have read of people having this issue after backwashing because of not rinsing, but this isn't it. I can literally turn off the pump...count to 20, turn it back on and I get the same result.

See the video here:

[okay..having trouble uploading video.. will keep trying]


Last summer I made a homemade slime bag with a 5 micron antibacterial pillowcase over the return jet and the stuff it caught in there was incredible! very fine slime.

Also, if the pool hasn't been vacuumed in as little as 2 days there are little pools of dirt everyone on the bottom.

So this year I've done the following: Change the sand and inspect/clean the latterals and stand pipe. I've also completely replaced the multi-port valve with a new one (I noticed the old one didn't spring back so I though perhaps that was the problem. I still get the same results as the video posted (that was taken this evening.. the video from last year is even worse!).

Now, below is a picture of the sand I got from the local "big box" pool store (they installed the pool and provided the filter, sand, etc). This is the same sand I replaced it with (because the local small shop that had actual No20 silica was closed). They market it as their "special" sand which I think is really rocks of some sort.. Is it possible this stuff is just too porous and is letting stuff through that normal sand doesn't?



This is why I was thinking I would solve all my problems with a cartridge filter in line after the sand filter. I wouldn't be working all that hard as the sand filter catches most of the stuff...but it's catching the fine stuff that the sand filter is letting through.

I thought I read that the pump is capable of around 70gpm but then read that 1.5 inch fittings would limit that down to 42gpm (but now told that may not be the case.. so thought perhaps I'm pushing water through the filter too fast..?).

Any insights would be appreciated!
Thanks! I'll return to try and upload the video soon...photobucket is being a little finicky at the moment)
 

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I used to have similar issues with my old pump/sand filter combination... Dirty water returning, couldn't get the water crystal clear, dirt/sediment that would collect on the bottom of the pool, etc.

Then I switched to a two speed pump a couple of weeks ago and started letting it filter the pool on the low setting...

Huge, huge difference. In my case the slower flow rate has improved filtration tremendously. From a swamp to clear in four days and no more sediment collecting on the pool floor. Even my wife just commented today that the pool looks cleaner/clearer than she has ever seen it before.

Sand filters really do seem to benefit from slower moving water.
 
pooldv said:
The whole problem sounds like algae to me. Do you have an FAS/DPD chlorine test? Perform the Overnight FC Loss Test (OCLT) to see if there is algae growing in the pool.

Give us a set of test results
CYA
FC
CC
PH
TA
CH
Click to expand...

Oh I've done all that. I SLAM'ed the pool for almost 2 straight weeks (I have the TFTestkit T-100)..The water is very clear..but just not crystal/polished like it should be.. and the pools of dirt on the bottom after only 1 or 2 days. From what I understand there is no reason the sand filter isn't catching all this stuff.

Maybe I do need the slower pump...
 
Okay..original post edited for the video. The effect is worse after I've vacuumed...it's almost like the stuff sitting on top of the sand finds its way through and back into the pool. I've also tried it after backwashing and rinsing, etc.. after a day or two when new stuff builds on top of the sand.. if I turn it off, then do something, then turn it back on I get the same thing...dirty water going back into the pool... so I'm also believing that when I don't see the dirty water..there is still some getting through
 
Yes, it is possible that the sand is too small. We have seen problems with that before. It is important to get properly sized #20 sand.

All filters operate better and more efficiently with lower pump speeds, either low on a 2 speed or low RPM on VS pump.
 
pooldv said:
Yes, it is possible that the sand is too small. We have seen problems with that before. It is important to get #20 sand.
Click to expand...

Oh..I would have thought it was perhaps too big, leaving more room for things to get through.

I'm going to take a sample to my local small pool guy and see if I can compare to regular silica pool sand... Love having a pool but I guess it was a great big assumption on my part that the pool installers know what they are doing! (ok..no more ranting on that front.. LOL).
 
Again, if you just went through a SLAM, that is likely to be dead algae which can make it's way through a sand filter since it is smaller than what a sand filter can filter. If you use some DE in the filter, it should help capture the dead algae.
 
mas985 said:
Again, if you just went through a SLAM, that is likely to be dead algae which can make it's way through a sand filter since it is smaller than what a sand filter can filter. If you use some DE in the filter, it should help capture the dead algae.
Click to expand...

I'll give that a shot, but these symptoms appear all year round. Wouldn't the stuff eventually get captured as the sand filter starts to be more efficient with stuff piling on top of the sand?

I'll try this. I'll put some DE in, and then do a thorough vacuum and backwash.. presumably that should get everything out of the pool and not reoccur.. Does that make sense?

My backwash hose goes behind my house into the drainage ditch...kids don't play in there but it is an open ditch... should I be concerned about the DE out back? I've heard it can be dangerous once dried.. just can't seem to get Cellulose Fiber in Canada (which was my preferred route). Thoughts?

Thanks for everyone's advice!
Paul.
 
Yes and yes.

However, if the DE does not work or makes it through the filter, then there is something definitely wrong with the filter. So either way you will have an answer.
 

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