De Filter Medium Replacement

[TS79]

Hi All,

I've been reading TV for a while but this is my first post so be gentle on me.

I've recently bought a house with a small / medium sized swimming pool and although I've had pools before this setup is a little different. It is an overflow pool where the water overflows all sides of the pool into a holding tank before going through the filters and back into the pool (nothing weird here).

The DE filter doesn't have a 3-way for backflushing so I guess the only way to clean the DE filter when the pressure gets high is to open the filter casing, remove the filter grid and hose it down (still no problem). Now comes the problem...how to I recoat the filter grid with DE powder? Since the pool is an overflow type there is no skimmer to pour the DE slurry into.

So do I :

1) Pour the DE into the overflow tank and let the pump suck it into the filter grid

2) Put the new DE directly onto the filter grid

3) Attempt to pour the slurry in through the filter basket upstream of the pump (being careful)

4) Another way?

I hope you pool guru's can help me out with the best way to do this. Also would it be beneficial to install a 3-way valve into the system?

Cheers,

Ste.

[Naam]

Put the new DE directly onto the filter grid

[fdimike]

Put the new DE directly onto the filter grid

I would contact the filter manufacturer to get their recommendation before doing anything. I'm sure you'll be able to locate a web site for whoever made the filter. I would be willing to guess that most filter manufacturers are represented here in Thailand. I have American made Hayward DE filters on my pool and there is no info in the instruction booklet which covers where to add the DE powder other than at the skimmer box.

You will also need to know how much DE powder to add to the filter with different size/brand filters requiring different amounts.

Additionally, it would be a good idea to install a 3 way valve on the filter in order to backwash it. Disassembling the filter each time you clean it will result in a costly waste of DE powder as the backwash option does not eliminate all the DE powder from the grids.

Another thing to consider is possible damage to the filter grids and Large "O" ring seal each time you open the filter.

[TS79]

Hi,

Thanks for the replies. Some further info about filter is:

Make : Star-Rite

Model : PLD50

Filter Area : 2.8 Sq M.

Precoat : 2.7Kg

Operating Manual only talks about putting DE slurry into skimmer, doesn't mention to use a 3-way valve. I guess I'll see how easy it is to put the DE direct onto the filter grid.

Ste.

[fdimike]

It's best to have a 3 way valve installed on the filter in order to backwash it as I've already said. You should locate the manufacturers web site and email them regarding where to add the DE powder.

Replacing filter grids on one of these filters here in Thailand can be expensive if you happen to add the powder incorrectly.

[fdimike]

Here's the manufacturers website. Pentair makes Sta Rite as well. Email them and ask for advice.

http://www.pentairpool.com/pool-owner/index.htm

Scroll to the bottom of the pageand you'll see a "Contact Us" option. Click and complete the form to get the correct information.

Hope this helps

[fdimike]

I read the owners manual on line at the web site for your filter and in the opening pages it suggests using a 3 way valve for ease of cleaning.

[TS79]

Thanks again for your help. It is much appreciated.

[WarpSpeed]

Sorry I came into this late.

Two ways.

First since it's a flooded suction system it sounds like correct me if I'm wrong? But meaning the pump is below the pools water level maybe? If that's correct then it is possible to shut the pump off and all the valves. Take a large bucket (like 5 gal equivalent) with the proper amount of DE in it and add water and stir making what is called a "slurry" mixture.

Open the pump trap and once you've cleaned it and the filter then open the return in the pool turn the pump on (yes with the trap open) it can run for a short time without hurting it, then slowly open any suction valve and let in some water enough so that the pump is sucking it down as it flows in and slowly pour in the slurry mix until it's all gone, shut the pump off and replace the lid and return to normal operation.. Don't put the slurry in the filter directly DE is very dense and it will cake on only the lower part of the elements and block up quickly plus it will fill in between the elements keeping them from actually filtering at all since it will be too thick for any water to pass through.. Remember the filter and it's contents are under strong pressure so it will not stir it as some think it will, it will only compact it further which is what it does on the elements..

Second tip especially if the pump is not a flooded suction system is to use the same bucket which should be a large one (like a 5 gal paint bucket) and again do the same thing with filling and making a slurry first..

Then get out your trusty vacuum head and hose presuming you have one, and sink it but without the pole attached. Turn on the vacuum line and make sure the pump is primed or you WILL have a huge, mess in your pool.

Once you've turned on the pump and made certain it's pumping @ full prime then put the bucket in the water holding it above the water line and not letting it tip over but it should sink to the water line in the bucket and be pretty stable weight wise and easy to manipulate, should be close to the top but not over. Pull the vac head up to the surface by the hose and then quickly pull out and place it in the bucket but don't let it lose prime, a small amount of air won't be a problem..

It will drain the bucket veeery quickly so dunk one edge to keep water coming in at the same rate the pump is taking it out and shortly all the DE will be gone and you can then lower the bucket all the way under the water surface and remove the vacuum hose from the pool to remove all the DE from the hose but again don't let it dry out the pump as it will all go through very quickly.. This may take some practice but you'll get the hang of it..

JFYI DE filters do not backwash well the DE gets very packed in between the elements as they are not too far apart so disassembling them is the best way to do it don't waste money on any 3 way valves Sta-rite got away from that set up years ago..

Does your Sta-Rite disassemble from the top? Or the center? Better yet, what model is it?

Let me say that a Sta-Rite is first rate stuff where DE filters are concerned so from that stand point you got a good filter..

[TS79]

Hi WarpSpeed, thanks for the reply and useful tips. The DE Filter is a PLD50 that opens from the centre, 2.8M2 filter area, 2.7Kg of DE medium. Pump rig is below the pool surface 2m underground.

I contacted Sta-Rite and their techie told me it would best to put the slurry into the overflow holding tank as close to the intake as possible. What I actually did was to make a contraption out of blue pipe. I took 3 metres of 4inch blue pipe, stuck a T-piece on the bottom of the pipe and capped the bottom of the Tee off. Then when I lowered this into the overflow tank, the outlet from the blue pipe was directly on the tank suction intake, then I just slowly poured the slurry down the pipe into the suction and job done. I could see the slurry getting sucked straight in. The contraption is now waiting the next DE replacement.

The Sta-Rite filter says that the DE medium should be replaced when the pressure drop increases 10psi from the startup pressure of the freshly cleaned filter. Mine has been running 6 weeks now and the pressure has only climbed 1psi (from 9psi to 10psi) so looks like it will be another few months before it needs doing again. Pool is sparkily clean too.

Cheers.

[WarpSpeed]

I would just clean it out on a regular schedule regardless keeping their maximums in mind in case it gets dirty sooner on occasion but in this case you're getting a long time between cleanings because you're doing a complete disassemble and not simply using a valve to backwash which is really inefficient if not more convenient.. A good schedule is about every 4-6 weeks...

Anyway with a flooded suction system give my technique a try you'll not bother with the clumsy pipe again. This technique has been used thousands of times and for decades in cases like yours so no harm will come to your equipment. I'm quite surprised the tech at Sta-rite didn't tell you about it but he may only be book taught and not have a lot of practical field experience..

Both of my techniques are far less complicated then the one you've been told to work out but especially filling the trap directly.. Just go slowly so it doesn't cake up in the pump basket..

Let me just add the reasoning behind not waiting until the pressure increases so much.

The efficiency of those filters does not allow for any grace period once they reach a pressure that high. in practice the get suddenly fully blocked and can actually dead head your pump which causes it to overheat, melt and then leak, worse case it can also ruin the pump housing.

In this case even if it doesn't get to that extreme at the very least it is putting inordinate pressure on the grids and will eventually tear them at weak points or collapse the internal ribs, in which case they prevent enough water to pass through making them nearly useless or in the case of rips or tears DE to bypass them and return to the pool making a considerable mess.