Upgrading from cartridge to sand filter

[kython89]

I'm wanting to upgrade from a CV340 cartridge filter to a sand filter.

My pool is ~35,000 gallons.

My pump:
Pentair Whisper Flow 011775
K63CXEBK THP 2.6

As I understand my pump is 120 GPM and the CV340 is rated for 140 GPM.

I think I've properly sized a Hayward W3S10T2 given the volume of my pool. The designed flow rate of that filter is 98 GPM. Given the pump is at the same level as the pool I'm assuming minimal head loss. Will my pump work or do I need to consider either A) the next size up of filter S360T2 that is rated for 78,000 GPM (10 hour) and keep my pump or B) get a smaller pump, possible dual speed, or variable speed. Is there a specific pump that pairs well with the W3S10T2?

Thanks in advance,
Kyle

 

[ajw22]

Why do you feel that is an upgrade?

 

[proavia]

Honestly, that's not really an upgrade in my book.
And this is coming from someone who had a 36" (700# of sand) sand filter for over 20 years. When it started leaking at a seam, I upgraded to a 420 sq ft cartridge filter. And I like the cartridge filter a lot better than the sand filter.

Chances are your pump will not achieve 120 gpm with your plumbing. But if it did, why would you consider a filter that can only handle 98 gpm instead of your present 140 gpm?

 

[bradgray]

Going to be the 3rd harmony in this choir...

Sand filter isn't an upgrade.
CV580 would be an upgrade.

Sand filters are dissimilar enough from your carts, you will want to do some more reading before you consider making the switch. They come with a different set of maintenance needs - and the tradeoffs may not actually satisfy you. You are going the other direction most do when switching styles.

I like certain things about both after over a decade of servicing both. On my personal pool, I use a cartridge system.

 

[kython89]

I'm wanting a sand filter so I can back flush rather than take the filter apart and clean each cartridge. When we first open the pool we are having to clean the cartridges several times a day due to the amount of dirt that gets in the pool. It takes 30+ minutes by the time you disassemble, clean each cartridge thoroughly, and put it back together. Vacuum a 10x10 ft area and its clogged again.

We are simply trying to reduce the amount of time we spend on getting the pool clean and keeping the pool clean.

Is there a possible option of adding a sand filter and keeping the CV340? I get it filters smaller stuff. But the sand filter would get most of the big stuff and then the cartridges won't need cleaned as much?

 

[Newdude]

Is there a possible option of adding a sand filter and keeping the CV340? I get it filters smaller stuff. But the sand filter would get most of the big stuff and then the cartridges won't need cleaned as much?

Multiple filters would reduce your flow if they didn't have their own pump/feed/return.

I also need to chime in on all the above. Equal sized filters for their style, are equal. A larger filter of either kind is an upgrade.

Which way you'd rather have to clean said filter is a personal preference.

IMO, your yard determines how well your pool filters. The crud it sucks up filters even finer crud. You will pick up that same initial crud no matter which way you go and it will determine how fine you filter after that. The only question is how long the sand filter takes to get a little dirty, and catch up to the other two.

 

[ajw22]

Your problem is your pool cleaner and not your filter.

IMHO vacuuming dirt from the pool into a filter is the worst type of pool cleaner, especially if you have a cartridge filter, for the reason you are experiencing.

Get a robot pool cleaner or two. Or get a pressure side cleaner that captures the dirt in its own bag. Lots of pool cleaner choices depending on how your pool is setup.

You can also install a cyclone prefilter that is supposed to capture debris before the filter. It’s more of a gadget we don’t recommend but may solve your pool opening problem.

 

[Newdude]

IMHO vacuuming dirt from the pool into a filter is the worst type of pool cleaner, especially if you have a cartridge filter, for the reason you are experiencing.

*into a small filter.

My large filter can go all season with vacuuming.

 

[ajw22]

*into a small filter.

My large filter can go all season with vacuuming.

Since we don’t know anything about the OP pool, how it is covered in the winter, or how much dirt needs to be cleaned up, we can’t judge if any size cartridge filter will work for him the way yours does for you.

Many things in pools are unique to a pool’s environment.

 

[Newdude]

Many things in pools are unique to a pool’s environment.

True that. But I can confirm that 500 sq ft carts can handle 80 oak trees on an acre with an 800 sq foot pool / crud vacuumer So.

This dirty was still below a psi increase that needed cleaning.

 

[Jimrahbe]

Kyle,

Other than the initial opening, how often are you having to clean your current cartridge filter during the season???

Just curious..

Thanks,

Jim R.

 

[ajw22]

You can also install a cyclone prefilter that is supposed to capture debris before the filter. It’s more of a gadget we don’t recommend but may solve your pool opening problem.

Waterco MultiCyclone 50 Pre-Filter 2-Inch | 200375 200370

Pool Supply Unlimited has some of the best prices when shopping for Waterco MultiCyclone 50 Pre-Filter 2-Inch | 200375 200370

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[kython89]

True that. But I can confirm that 500 sq ft carts can handle 80 oak trees on an acre with an 800 sq foot pool / crud vacuumer So.

This dirty was still below a psi increase that needed cleaning.

View attachment 565374

Our filters don't get near that dirty and the pressure spikes from clean to dirty, if I recall 30 PSI, and there is noticeably reduced flow at the jets.

In the filter basket near the top there have always been 1 or 2 water bubbles at the very top. When the filters are clean the system works fine and we have ample flow at the jets. Is it possible that if there is a suction side leak that it can make the filter pressure gauge rise prematurely and reduce the flow to the jets?

Given that cleaning the filters fixes the problem for many minutes to hours I've been assuming that isn't an issue....

Your problem is your pool cleaner and not your filter.

IMHO vacuuming dirt from the pool into a filter is the worst type of pool cleaner, especially if you have a cartridge filter, for the reason you are experiencing.

Get a robot pool cleaner or two. Or get a pressure side cleaner that captures the dirt in its own bag. Lots of pool cleaner choices depending on how your pool is setup.

You can also install a cyclone prefilter that is supposed to capture debris before the filter. It’s more of a gadget we don’t recommend but may solve your pool opening problem.

We halve a Dolphin Premier. Perhaps I need to rely it more for this type of cleaning. I have the leef bag in it right now. My perception is that it fills up fast with this much dirt. The M4 in my signature got water in the motor box and released the magic smoke last year.

Kyle,

Other than the initial opening, how often are you having to clean your current cartridge filter during the season???

Just curious..

Thanks,

Jim R.

Every 2 weeks typically.

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We might consider something else like this if everything else appears to check out fine.

This the general progression. I'm showing the cover because someone asked about it. It has a few small holes in. We also think we get alot of dirt that is on top that falls down in the pool when we try to remove the cover. It's a bit unwieldy and not obvious how to remove it without it falling in the pool during the process.




I appreciate all the responses and people being willing to help. I never would have gotten it crystal clear the last couple years without the help of TFP. We know we'll get back to it but we haven't gotten their yet.

Kyle

 

[ajw22]

Put duct tape on both sides of the small holes in the cover.

 

[Newdude]

Our filters don't get near that dirty and the pressure spikes from clean to dirty, if I recall 30 PSI, and there is noticeably reduced flow at the jets.

You have a large pool, maybe even larger than me, and smaller filters.

The point was with a large enough filter, it's no longer an issue.

Whichever way you go, the size is more important than the style. Wanna switch to sand because you would rather have those +/-'s ? Great. Get a honking sand filter when you do to lessen the cleaning frequencies.

 

[Jimrahbe]

Every 2 weeks typically.

Kyle,

That is crazy...

If I had to clean my Cartridge filter every two weeks, I too would be looking for something else...

For reference, I clean my filter once or twice a year at the most and my pool stays open year round.

Do you clean your current filter because the flow decreases, or just because someone told you that is what you should do??

Thanks,

Jim R.

 

[1poolman1]

I'm wanting a sand filter so I can back flush rather than take the filter apart and clean each cartridge. When we first open the pool we are having to clean the cartridges several times a day due to the amount of dirt that gets in the pool. It takes 30+ minutes by the time you disassemble, clean each cartridge thoroughly, and put it back together. Vacuum a 10x10 ft area and its clogged again.

We are simply trying to reduce the amount of time we spend on getting the pool clean and keeping the pool clean.

Is there a possible option of adding a sand filter and keeping the CV340? I get it filters smaller stuff. But the sand filter would get most of the big stuff and then the cartridges won't need cleaned as much?

That's a beautiful area for everything except a pool. Its like my backyard (though I think my entire yard would fit into that pool).
If you want a sand filter, get one, and I would for that yard.. You will have to learn a different set of maintenance routines, but I have never had a customer disappointed when changing from cartridge or DE to sand, especially one that large. Just be sure you have a place to run the backwash/rinse water without causing damage. The chemicals won't usually cause an issue, but the run-off could.
The best thing your could do if you do make the change is add a VSP and run it long and slow, don't worry about GPM. Find a slow speed that works for your area. Hopefully you have, or are planning on, a SWG as well.
When VSP first came out, that was the recommendation, a VSP with a sand filter. If you keep up with your chemicals, you will not notice a difference in water clarity.
Watch the swimming/diving events at the Olympics this Summer. Go to any large pool, like a high school or college. Go to a waterpark where the water looks like milk at the end of the day and is completely clear the next. Virtually all are filtered with very large sand filters, usually three as they use a different backwash sequence that is also usually automated.

 

[kython89]

This is what my dirty filters look like that drastically reduce flow and cause pressure to increase.


Pressure after cleaning filters.



Pressure a couple hours later

Filter basket. Its always had about this many bubbles since we bought the house. May be a little hard to see but it wouldn't let me upload a video of the bubbles.

Do you clean your current filter because the flow decreases, or just because someone told you that is what you should do??

Flow decrease prompts me to check the pressure gauge.

 

[Newdude]

Here is the same filter posted above in post #10, but after clearing a spring swamp. It looks much closer to yours.




You need to run an overnight test. If you lose FC with no UV, then algae is brewing and your filter is working great at removing it.

Please read :
Overnight Chlorine Loss Test

 

[bradgray]

+1 on the algae test.

Food for thought; what if you simply installed a 3-way between your pump and filter and vacuumed to waste at the start of the season? Ideally none of that junk goes through any filter.

I'd invest in that $80 valve and a new VSP instead of a sand filter if it was me. Assuming the pool is well behaved the rest of the year.