Sand vs DE, why not both?

[nasomi]

I ran a sand filter for years, it worked well enough, but I had to vacuum to waste if it was heavy because the particulates just wouldn't get caught, and green would come out the jets. Last year my father filled in his pool, and gave me his DE filter. I put it on, and it worked great, but found it filled rather fast. So when putting everything together this spring, I saw my old sand filter behind my shed and thought, "why not?" Hoofed it down to home depot and picked up a pile of pvc fittings, and threw it together.

My first issue: Earth wouldn't pass through the sand very well, so I had to add an earth adder before the DE filter. Used a T fitting, adapted 1.5" to 4", and put a screw on cap. It comes off, pre-mixed earth/water pours in nicely, and gets capped again.

Now it's running well. Dumped sand 5 times before having to change the earth the first time. My pool got dirty in the fall before I covered it so it's a mess right now. I have a leak between my skimmer and the pump, so I have to dig that up and repair it as well.

 

[jblizzle]

Welcome to TFP!!!

Here are reasons I would not:
1. Added expense to buy and maintain 2 filters.
2. Added labor to maintain 2 filters
3. Added head loss and thus lower flow rates through 2 filters.
4. Any single filter type can maintain a crystal clear pool.

 

[Patrick_B]

Ok then, welcome to TFP!

 

[nasomi]

I would think that, as long as the pressure is not high on either of the filters, it shouldn't reduce flow any. I already had the filters, so no out of pocket expense for them.

Question though, how much sand should go in the sand filter? I always put one bag, 50lb, it comes up pretty high at that level. But I see some recommending 200-300lb of sand. I don't think I could FIT that much sand in that filter. I'm going to take the filter apart today, I can get pictures inside if that helps. All labels on the filter are completely washed out and I have no idea the make or model of it.

Edit: I should say, backwashing the sand is much easier than changing the earth, cheaper too. I like hte simplicity of hte sand, it just has never filtered properly when it comes to heavy stuff. Since I have all the equiptment already, I wanted to try it. Thus far it's worked really well. I rebuilt the multi-valve for the sand yesterday, now it spins easily and the leaks are gone. Today I need to redo some of the fittings as there's some leaks.

 

[jblizzle]

Well the pressure is going to be lower in the second filter due to the head loss of the first filter ... and if you had a pressure gauge after the 2nd filter, it would be even lower ... equating to lower flow rates.

There are many different sizes of sand filters ... from 50 pounds to 1000s of pounds of sand.

 

[tim5055]

Question though, how much sand should go in the sand filter? I always put one bag, 50lb, it comes up pretty high at that level. But I see some recommending 200-300lb of sand. I don't think I could FIT that much sand in that filter. I'm going to take the filter apart today, I can get pictures inside if that helps. All labels on the filter are completely washed out and I have no idea the make or model of it.

You may need to pok around on the Hayward web site to figure out the model. Every brand/model uses a different amount of sand. You could PM user "Hayward Pool" and see if he can identify it from the photo.

But, when it comes down to it I agree with Jason as to having two filters in series. Now, if you could rig it up to be selectable, that might add some value. But I'm not sure if it would be enough to overcome the maintenance of two filter systems.

 

[nasomi]

Lower pressure typically means better flow though. The first filter sitting at 10-12psi, the second sitting at 8-10psi, and water is moving quite quickly. The pump is a 220v 2hp if memory serves. When pressure drops on the second filter, the first is full and I flush and it returns to normal. When the pressure raises on the second, it's full and I pump it down.

There should be almost no pressure after the second filter, it's free flowing back to the returns in the pool.

- - - Updated - - -

You may need to pok around on the Hayward web site to figure out the model. Every brand/model uses a different amount of sand. You could PM user "Hayward Pool" and see if he can identify it from the photo.

But, when it comes down to it I agree with Jason as to having two filters in series. Now, if you could rig it up to be selectable, that might add some value. But I'm not sure if it would be enough to overcome the maintenance of two filter systems.

I am not sure the sand filter is hayward, the earth filter is and the pump is. All hayward sand filters I've seen have plastic housings, where-as this one is chrome. I'm not really worried about the labor, just trying to pre-filter with sand to save on the hassle of changing earth.

 

[jblizzle]

Well, you have a big pump that is able to push through the filters ... Really your pump is oversized and you could save money on power with a smaller pump.

If it works for you great, I just do not want other members running out and installing 2 filters for no good reason.

 

[nasomi]

I'm not reccomending it, I just wanted to share my experience and get some feedback. I had to change the earth weekly last year, just to keep it crystal clear. It's in full sun all day. I had to pump it down every day, sometimes twice. Even keeping chlorine high, the fight with algae has always been a losing battle. I've had my water tested many times, all parameters are good. I had the parts, so I put it together to see what happened.

 

[jblizzle]

the fight with algae has always been a losing battle. I've had my water tested many times, all parameters are good. I had the parts, so I put it together to see what happened.

And now we find out the real problem. You are not testing your own water and are trying to battle algae with filters.
Algae is a chemical problem not a filter problem.

If you want to take control of your pool, you need to invest in one of the Recommended Test Kits and then eradicate the algae by following the ShockLevelAndMAINTAIN Process. Then keep your FC level above the minimum for your CYA level as shown in the FC/CYA Chart and you will never have algae again.

How do you chlorinate your pool?
Have you discovered Pool School yet? Start with these:
ABCs of Water Chemistry
Recommended Pool Chemicals
How to Chlorinate Your Pool

 

[duraleigh]

I had to change the earth weekly last year, just to keep it crystal clear.

That is a function of your water chemistry and not any kind of particular filter. A Sand, cartridge, or DE Filter, properly sized, will keep your pool absolutely crystal clear IF your water chemistry is correct.

If your water chemistry is off, there is NO filter that will keep your water crystal clear.

 

[nasomi]

I shock weekly and keep 2 tablets in the skimmer at all times for chlorine. I was testing it myself with the standard kit, and all was fine, but still had issues. I went to Leslie Pools and had them test it and they would find this or that, I'd treat it, and get to spec, but still had algae issues.

 

[jblizzle]

Please re-read my previous post and the associated links.

Clearly everything was not "fine" .. pool store testing is worth what you pay for it.

 

[tim5055]

I went to Leslie Pools and had them test it and they would find this or that, I'd treat it, and get to spec, but still had algae issues.

We call that being "pool stored". One trip it's phosphates, so buy some PhosFree. The next time it's cloudy water, so buy some floculant. Oh, you see algae - buy algecide. Using our system, none of those things are used.

Read the links Jason provided - understand we base our methods on accurate testing and only adding what the pool needs, when it needs it. Generally that ends up being chlorine (not solid forms) and acid to control pH.

 

[Richard320]

I'm not reccomending it, I just wanted to share my experience and get some feedback. I had to change the earth weekly last year, just to keep it crystal clear. It's in full sun all day. I had to pump it down every day, sometimes twice. Even keeping chlorine high, the fight with algae has always been a losing battle. I've had my water tested many times, all parameters are good. I had the parts, so I put it together to see what happened.

Right there is where I hear the alarm go off.

True story: I worked three summers at a Cub Scout Day Camp that had a pool. The place was a dustbowl. Every day 200 dirty 7-10 year olds went in that pool. Let it settle for an hour and the vacuum would leave white stripes across the tan floor. And even with that load, the old DE filter didn't require backwashing but twice a week. And you're backwashing every week?

No - you've got algae growing. It's too small to see with the naked eye, but it's there. And then you kill some of it and the bleached cacasses get filtered out, loading your filter. And the "shock" wears off and it starts growing again, until the "shock" kills a bunch more. That's what's loading up the filter. The clogged filters are but a symptom of a bigger problem

"parameters are good" says nothing. What is "keeping chlorine high"? High relative to what - the industry standard 3 ppm regardless of the CYA level? What IS the CYA level after feeding it a steady diet of pucks and powdered shock? Did Leslies write "99" on the report? That's poolstore code for "Off the scale."

It's really easy to end up with CYA over 200. When I took over my pool, that's where I was. To maintain enough active free Chlorine to keep algae at bay, I had to maintain a minimum of 18 FC. The water stayed clear and we swam in it no problem. If you took a sample of that in to the store, they'd tell you it was too high, and sell some Thiosulfate to reduce it... nevermind that the sun would do it for free in a couple days, not that it needed reducing anyway.

Bottom line - the reason for all of us doing this is that we can teach you how to fix it. You can have a pool like mine, where a single DE filter requires backwashing no more than twice a year, and the water is clear enough to toss a quarter in the deep end and call heads or tails from the deck. Where it doesn't smell like chlorine and nobody complains about itchy skin or burning eyes, even after swimming underwater with their eyes open.

 

[tim5055]

Right there is where I hear the alarm go off.

True story: I worked three summers at a Cub Scout Day Camp that had a pool. The place was a dustbowl. Every day 200 dirty 7-10 year olds went in that pool. Let it settle for an hour and the vacuum would leave white stripes across the tan floor. And even with that load, the old DE filter didn't require backwashing but twice a week. And you're backwashing every week?

No - you've got algae growing. It's too small to see with the naked eye, but it's there. And then you kill some of it and the bleached cacasses get filtered out, loading your filter. And the "shock" wears off and it starts growing again, until the "shock" kills a bunch more. That's what's loading up the filter. The clogged filters are but a symptom of a bigger problem

"parameters are good" says nothing. What is "keeping chlorine high"? High relative to what - the industry standard 3 ppm regardless of the CYA level? What IS the CYA level after feeding it a steady diet of pucks and powdered shock? Did Leslies write "99" on the report? That's poolstore code for "Off the scale."

It's really easy to end up with CYA over 200. When I took over my pool, that's where I was. To maintain enough active free Chlorine to keep algae at bay, I had to maintain a minimum of 18 FC. The water stayed clear and we swam in it no problem. If you took a sample of that in to the store, they'd tell you it was too high, and sell some Thiosulfate to reduce it... nevermind that the sun would do it for free in a couple days, not that it needed reducing anyway.

Bottom line - the reason for all of us doing this is that we can teach you how to fix it. You can have a pool like mine, where a single DE filter requires backwashing no more than twice a year, and the water is clear enough to toss a quarter in the deep end and call heads or tails from the deck. Where it doesn't smell like chlorine and nobody complains about itchy skin or burning eyes, even after swimming underwater with their eyes open.