sta rite system 3 cardtidge as good as de?

[waterbear]

i guess i should give some background and maybe you guys can help make a recomendation...

my pool is a 26' kidney, about 15,000g or so. problem is, it's really old. it looks nice, but the plumbing is not ideal. there is only one 1.25" suction line running from the skimmer and the bottom drain is full of gravel (below the cover). i'm not sure how it got there, but i know it's not functioning so the deep end doesn't get alot of attention. when i run the filter alot, it keeps up with the pool pretty well, but after a party or any thing less than an 8 hour cycle, it can turn bad and gets out of control easily if i don't really stay on it. it has a 3/4 horse pump that runs good, but looks as old at the pool and has a vintage sta-rite spin DE 25 sq ft. another problem i have is there is no sewage line near the filter, so for the last umpty years, the pool guy has been backwashing (well, who knows where). i'd like to not have to backwash, but i'm concerned getting away from DE and not being able to keep up with the pool as it's tough enough already.

i've been going back and forth between the pentair fns plus 36 sq ft and the starite mod cart in 300 sq ft....

Spin DE filters really can't be compared to modern vertical grid DE filters. If you really like the polished water that DE gives you might want to look into a more modern one! I think you might be very happy with one! You can always add a separation tank to it to collect the DE that is backwashed out so you only have the backwash water to deal with.

[Poconos]

Evan,
I don't know where you're getting your information as it is incomplete and contrary to almost everything that has been posted about sand filters in the past. First, channeling will occur with an oversized pump. Why don't you state that? When the pump and filter are properly sized this is not an issue. Next, backwashing will break up any clumps on the surface unless something has gotten into the filter to goo it up, like baquagoo. Next, sand doesn't have to be routinely 'cleaned', again, unless something has gotten into it to cause problems. Finally, for 9 seasons I never had a problem and the only time I dumped the sand was to make a unique addition to let me drain it better for winterizing. And I put the same sand back. Never added, never changed, never got my hands messy.
Now...I'm tempted to exercise my power as a moderator and lock this thread but I won't. Not yet. It has gotten completely off topic and as Dave said, is misleading to inexperienced people. Enough of this sand filter nonsense and misinformation. Guess I'm just a little rattled right now.
Al

[waterbear]

You might want to consider moving it to the china shop then. Channeling can occur even in a free flow sand filter that is not pressurized. It is the nature of the beast when filtering with sand. Organics, oils, and scale can collect on the sand and backwashing will not effectively remove them and over time they will take their toll. These same organics, oils, and scale also cause DE to clump and bridge and are what effectively 'wears out' a cartridge. It is true that a pump that is oversized can cause channeling and other problems but that is not the only reason it occurs. Cleaning the sand and declumping it is not the same as replacing the sand. All filter mediums get dirty with use and a dirty filter medium reaches a point where it is just not as effeicint anymore.

[coryinsocal]

thanks alot for helpfull (on topic) replies. i think i'd also prefer the de, so i may just do the teardown instead of backwashing when needed. it shouldn't be too often as the 36 sq ft is pretty oversized for my pool. as a side note, i've since found out that long beach,ca doesn't even allow backwashing of DE to the sewers without a separator anyway. only sand can be backwashed to the sewer without treatment.i figure i can get by with the breakdown method till i'm forced to buy a separator.... does anyone forsee any major problems with a plan like this?

on this note, since the separator is just a second trap, is there any reason to spend alot on one? should i just try to go cheap? also, i heard that adding a separator can decrease the backwash effectiveness due to gpm limiting characteristics...

[JohnInSoCal]

I guess this is kind of like a religous debate or coke/pepsi but I'll throw in my .02 I have tried both modern DE and cartridge systems and prefer the DE. I suppose a small cartridge may be easier to deal with than a DE filter but the 4 cartridge large sq/ft hayward is a big pain to clean and takes several hours if you want to clean it well. Sure you can take it out and give it a quick squirt and throw it back in the filter and consider that a cleaning job. But dirt/grime really gets into all those little pleats and it seems to take forever to clean those.

After 1 year with my 4 cartridge hayward I decided to switch to DE because I figured DE couldn't be any harder than the darn cartridge to clean and to replace 4 cartridges costs a small fortune, almost as much as a new filter. I was amazed at the clarity difference it made as well. Perhaps my cartridges were just bad but they were not even 1 year old, but the DE made the water really sparkle. And at night you can definately tell a difference by looking in front of the light.

Because my DE system had a problem I ended up tearing the system down a couple times to find a hole and didn't find it very difficult at all, it was faster than a full clean of 4 cartridges. So I am definately sold on DE over cartridge. I can't say anything about sand as I have never tried it.

-- john

[coryinsocal]

i gues now i'm looking into separation tanks (which should maybe be another thread). in addition to the innefficiency during backwash question above, does anyone here have experience using one where you return the separated water to the pool? most manufacturers say that you can do this, but it seems to me, that unless the tank filters as well as a de filter, you'd get a buch of crud making it past the sep tank and back into the pool. does anyone have any experience with this?

[waterbear]

IMHO (and this will probably start another debate!), DE filters should be broken down and cleaned, not backwashed. My reasons are as follows:
1. when you back wash you really don't know how much DE has washed out so you really don't know how much DE to replace...too little and you will not have good filtraton...too much and you might get bridging between the grids (and if you have ever had to pick away at rock hard DE stuck between the grids you understand what I mean!)
2. Backwashing forces water backwards through the grids....If you run a DE filter without DE, even for a short time, you run the risk of dirt clogging the grids and the grids getting coated with oils and organics. You then have to break the filter down and clean the grids...when you backwash you are still forcing dirty water through the grids (backwards) and the same thing can occur.

As far as "bumping' a DE filter....knocking the DE off the grids so the dirt can mix with it and then recoating the grids is not a good idea, IMHO. Dirty DE is dirty DE!

Just my 2 cents!

[Poconos]

One final note from me on this thread. Anyone contemplating buying a filter should read all the stuff that's been posted on this forum and the 'pool construction and repair' and 'AG pool equipment and construction' forums before making a decision. The subject of filters has been discussed in great depth and there are all kinds of views concerning water clarity, cost, and maintenance.
Al

[Rangeball]

i've been going back and forth between the pentair fns plus 36 sq ft and the starite mod cart in 300 sq ft....

I've had the pentair FNS+ 36 for several years now. No mechanical issues at all.

So far this year, I've not had to backwash or clean once. It's amazing what happens when you stay ahead of your pool I am at 13 now, but I'm pretty sure it's due to cotton wood trees with no skimmer sock.

My filter pressure runs at 10 psi at start up. It's recommended to backwash when it goes up 10, so for mine at 20 psi. What I do after I've backwashed is add de slowly back to it until the pressure again hit's 10 psi. This way I can avoid a complete teardown unless absolutely necessary.

[coryinsocal]

I've had the pentair FNS+ 36 for several years now. No mechanical issues at all.

So far this year, I've not had to backwash or clean once. It's amazing what happens when you stay ahead of your pool I am at 13 now, but I'm pretty sure it's due to cotton wood trees with no skimmer sock.

My filter pressure runs at 10 psi at start up. It's recommended to backwash when it goes up 10, so for mine at 20 psi. What I do after I've backwashed is add de slowly back to it until the pressure again hit's 10 psi. This way I can avoid a complete teardown unless absolutely necessary.

yeah, i've pretty much decided on this one over the last couple days. i've found it shipped with a multiport for under $500, so i think i'll order soon.
do you mind my asking how big you pool is and how long you run your pump?