How do folks backwash?

[SL Dan]

I'm wondering how all of you backwash your filters, what kind of methods you use.

I have to backwash pretty often - though my neighbor, who also has a pool, say I shouldn't have to but should instead tear down the filter and just clean it. But I'd be doing that every month.

Anyway, for years I didn't maintain it but since taking over about 7 years ago, the water just spills out right near where the filter is, and my other neighbors complain. So I'm looking for information about backwashing - how often, where the backwashed water goes, etc.

Many thanks.

[PoolDoc]

Traffic is low on the forum currently, so you're not likely to get many answers. I can make a couple of observations that may be helpful:

1. If filter backwash runs on to the street or your neighbor's yard, it is technically a Federal violation. This situation has a complicated history, and the violation is rarely enforced, except . . . where there are PO'd neighbors who get upset, declare "there OUGHT to be a law", and go looking for one. It's best to avoid that situation. In Cali, the local enforcement authorities WILL be aware of the relevant law and enforcement process.

2. In the West, because of water restrictions and other issues. many pool owners use cartridge filters. If you buy one that's large enough, you can probably go 3 months between cleaning. But there are potential problems if you have a large pump, or a variable speed pump. I've listed a recommended filter below, but you should tell me what pump you have, and let me make sure there's no problem BEFORE you purchase.

3. If the problem is the DE powder in the backwash, and not the water itself, you can use DE socks to capture the waste powder. BUT . . . you'll probably need to manifold multiple socks together, to avoid blowing out the sock. 6 Pack DE Filter Backwash Sock (http://www.amazon.com/exec/obidos/ASIN/B06XG6QYLV/poolbooks/)

________________________________

Recommended cartridge filter:
Hayward C7030 SwimClear Cartridge Filter, 700 sft (http://www.amazon.com/exec/obidos/ASIN/B00CG4BSCM/poolbooks/)


Extra set of cartridges:
Hayward CX591XREPAK4 Replacement Cartridge (http://www.amazon.com/exec/obidos/ASIN/B00CG4C466/poolbooks/)


Cautions: There are other filters, but AVOID the StaRite System3.
Get an oversize filter. Really! There are many reasons.
Get a multi-cartridge filter. Filters with huge single or double cartridges are unmanageable.
Get an extra set of cartridges, so you can soak and wash properly.
Failing to clean dirty cartridges can destroy them if you have a powerful pump.
Make sure your filter gauge works. Replace it as necessary


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[PoolDoc]

Moving thread to pool operations forum section . . .

[SL Dan]

Thanks, i was entirely unsure if I had it in the right place.

My filter is a Purex (Pentair) 2000, 36 sq. ft. The pump is a Pentair Whisper-Flo (anything but), 3/4 HP.

I'll be damned if I can figure out where the various pool guys backwashed to. Maybe they had their own backwash hoses.

[PoolDoc]

Looked at some old drawings; I'm fairly sure that's not really a back-washable filter. It's no longer made, so I can't find a manual, but I would imagine the service guys just opened it, and a port or drain at the bottom, and washed it down.

DE powder is find in garden soil; you just don't want it blowing around and getting into your lungs.

[SL Dan]

There's a whole rig on bottom where, in one position it's normal and the other it says backwash.

Can I add a few images?

[PoolDoc]

Sorry; can't help.

I've never been around that filter, and didn't see a manual online.

[SL Dan]

This is what I have:

https://www.manualslib.com/manual/121727/Pentair-Pool-Products-Sm-Smbw-2000.html#product-Spira-Mite%20SM%202036

[PoolDoc]

Looks like that manual is only partially readable? And, I assume you do NOT have the associated separation tank?

Still, with my limited experience with residential pressure DE filters (most of the DE filters I've worked with were giant commercial vacuum DE filters), it's worthwhile to periodically break down the filter. Unlike sand filters, backwashing DE filters only seems to work partially. Full cleaning requires opening the filter, ESPECIALLY if you haven't done so in a while.

[SL Dan]

I've done it 4 or 5 times so far this year. And right, I don't have the separation tank. Until I DL'ed that manual, I didn't even realize there was a separation tank. This filter was gotten by our last pool man.

But I'm wondering what most people who have DE filters do with waste water/DE/algae when they backwash.

[PoolDoc]

It sounds like you are looking for a discussion on the topic; there's probably enough traffic on TroubleFreePool for a discussion. Not sure about PoolSpaForum. You may want to register and post your ? on TFP.

[SL Dan]

Okay - I didn't know about that site. This place is my go-to. Thanks.

[PoolDoc]

Thanks, but there's a fair bit of traffic here from Google searchers, but very little from registered members . . . so not much new discussion. That's not something that will change before next spring, for a variety of reasons.

[SL Dan]

Hi Ben,

Can you explain why I should get such a large filter for a 20,000 gallon pool? I'm about to pull the trigger on something.

[SL Dan]

Oh, and because of the DWP rebate program, I'm going to install a Pentair variable speed pump.

[PoolDoc]

All filters function better with low flow rates per sft of filter area. This is ESPECIALLY true with sand filters.
All filters run longer between cleaning with low flow rates.
High flow rates tend to damage filters. High flow = high differential pressure which KILLS filter cartridges, especially modern 'high-capacity' cartridges with pleats that are too close together. High flow may damage DE membrane support grids. High flow WASHES SAND OUT of the filter during backwash, and PUSHES DIRT THROUGH the filter during operation on sand filters.
It is still possible to develop high differential pressure, across the media, with oversize filters but it's much less likely.
Is that enough? If you need more, you'll have to wait till later this weekend.

By the way, REGARDLESS of filter type or size, you need a WORKING pressure gauge to monitor filter ops properly.
NO FILTER should operate at over 30 psi absolute (unless it's the new-ish Pentair high-pressure sand filter).
NO FILTER should operate at more than a 7 or 8 psi pressure rise (clean to dirty). Cartridge filters should be cleaned at a 5 psi rise (old style) or 3 psi rise (new style with pleats too close).

[SL Dan]

Thank you.

If there's more to say, of course I want to know.

[SL Dan]

BTW, I've ordered the recommended filter, the Hayward C3070, and a Pentair Superflo VS. They'll be installed next Friday, September 6th.

[PoolDoc]

I'll try to get back to this before Tuesday, but I'm glad. I hope it works out really well for you.

One of the additional reasons for an oversize filter that I hadn't mentioned is the problem of VS pumps. Most of these pumps -- including the Whisperflo VS -- are actually extremely high volume 3HP pumps that can pretty much DESTROY most smaller filters if they are inadvertently run at full speed / full power! They ought to come with a key-locked maximum setting, based on the filter & piping they were matched to, so this couldn't accidentally happen.

The Pentair Superflo VS is apparently 'just' a 1.5 HP pump (PLENTY large enough for a 20K gal pool!), so the problem is reduced. Even so, that pump can potentially generate nearly 40 psi, if driven against a dirty filter that is undersized!

[SL Dan]

The pump and filter were installed yesterday, and so far they're working very well.

[PoolDoc]

Thanks for the follow-up. If you can, please set your phone to remind you, and let me know how it's going in a month.

One of the problems with the forum, over the years, is that a lot of advice has been given that disappears into a black hole of 'no longer term feedback'.

Ben