How will sawdust affect my filter cartridges?

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D

DeptOfMeteors

Well-known member
Jul 8, 2020
124
Ottawa
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-15
I don't know how old the cartridges are--I only got them last year w/the house. But the pressure keeps going up in the filter. So I dunked them in a cleaning solution overnight and when I took them out and I installed them and started the pump the pressure was very low, at first. Unfortunately, there was a fair bit of sawdust floating on the top, from the work that was being done on my deck. By next morning the pressure was high again and air was coming out of the jets. So I took the cartridges out and hosed them down. Putting them back in, the pressure was on the high side still, but there was still good flow. A few hours later, high pressure, and air coming out of the jets.
I'm not certain if this is a matter of my cartridges being shot or just a lot of problems with the water, and I don't know how much of that was down to the sawdust. I have a feeling it only took a few hours for the pressure to build up after I soaked them, but I could only be sure that the pressure was high the next morning.
This filter has 4 cartridges that are 7" in diameter and about 3' high. If I decide that these cartridges need replaced, I'm probably going to just get a sand filter instead.
 
I doubt the sawdust is the culprit. I would be suspicious of the overall water chemistry. Can you post a full set of water test results? Hopefully you already have a Taylor K-2006C or TF-100 test kit. That would be our first step in evaluating your situation.
 
It's taking so long for me to open this stupid thing, I hope I don't blow up my test kit. Ok, let's see...
Chlorine: non-existent (looks like my shock from the other day wore off
pH: 6.9
CH: 375ppm (although I find the drops very difficult to count. It may be as low as 300ppm)
TA: 20 although I was surprised at how quickly the colour changed. It might be 10.

So is that the sort of thing that can clog a filter and make the pressure go up? Would the solution involve soaking the cartridges again overnight or would whatever TA- pH-raising measures you recommend be good enough?
 
FC of 0 means it's highly likely that algae is growing & that can fill your filter fast.
To get started, we need to do a few things:
1) fill out your signature with your equipment, test kit, etc. so we know what we are working with.
2) do some reading. "Dump and pray every few days" isn't a pool management practice we advise.
Pool Care Basics
PoolMath
3) First things to address are your chlorine (add liquid chlorine) and pH needs to come up a tad (soda ash or borax). Since your TA seems low, Soda Ash (Arm & Hammer WASHING SODA) would help with both. Use PoolMath to figure out the right amount based on your pool volume.

Edit: I originally recommended Borax for pH & TA up, but Soda Ash is probably the better choice here as it will have a stronger effect on TA. Really either will work well in this situation.
 
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Also, have you used anything else? Algaecide of any kind? Clarifier? Phosphate Remover? Those things can quickly fill a filter and are almost always pushed by pool stores if you've been visiting them.
 
Please note what I'm up against:
  1. I can only run the pump for less than an hour, then the flow comes to a dead stop, so dealing w/the cartridges should be the first order of business
  2. I'd like to do this w/as few iterations of going to the pool store, coming home and trying stuff as possible. The next time I'll be there is tomorrow morning, so I should know as much as I can about what I need as possible
I'm pretty sure I didn't use any clarifier or phosphate remover, but I did use a pool opening kit which I think included an algaecide.
 
I would suggest staying out of the pool store entirely if possible.
You can buy the washing soda (not baking soda...WASHING SODA) or borax (if you can't find washing soda) in the laundry aisle at most supermarkets.
You can buy liquid chlorine at big box stores (Home Depot, Lowe's, Menards, whatever you have up there).

Without addressing whatever is gumming up your cartridges, you're going to be stuck. I suppose it is possible that the cartridges just aren't getting all that clean when you do a cleaning; so are getting filled up quickly. In that case, a new set of cartridges would likely help, but it's hard to know and it's not like they're cheap.
(Although, having 2 sets that you can alternate and clean one while the others are filtering has certain advantages).

You were originally asking whether sawdust could do this. How much sawdust are we talking?
Sawdust is basically cellulose fibers. Particularly treated and graded ones are actually used as an alternative to DE filter media. So it could definitely clog a filter, but I would think it should wash out pretty well. You don't still have sawdust in the pool do you?
 
Also, how are you cleaning the cartridges? You mentioned soaking and you mentioned hosing off. Usually, you use a hose end sprayer (or your thumb) to create a strong jet of water to make sure you get all the stuff out between the pleats.
 
Oh right, you mean bleach. I'll put that on the grocery list then.
What happened was:
  • Monday evening I dropped the cartridges into a cartridge cleaning solution
  • Tuesday evening
    • I took them out, hosed them down, and put them back in the filter.
    • The surface of the pool had sawdust. Not a huge amount, but some work guys were working on my deck and some of the sawdust got onto the water. So imagine what would be a moderate amount for what it would take to replace a few boards on a deck. If it was untreated, natural plant waste, it wouldn't have seemed like much, but sawdust from treated wood could be a different story, for all I know.
    • The pressure started out very low and stayed very low for several minutes.
  • Late Tuesday night, I suspect that the pressure went up, but that's just speculation
  • Wednesday morning the pressure was as high as a kite and air was just coming out of the jets.
    • I removed the cartridges again and hosed them down
    • Put the cartridges back, turned on the pump, the pressure was kind of high, but the flow was good.
    • About an hour later, I was back where I started that morning
The technique I have for hosing down the cartridges is using a head that forms an arc so as to get all the water into several columns of pleats. It should have been thorough enough to do as good a job as was possible w/that equipment. There's no visible sawdust anywhere, so if they are clogging up the pleats, they would have to be invisible by now.
One big question I've been banging my head over is if the pool could be so dirty as to clog even the cleanest filters in just a matter of hours, or if all this is happening because the filters are shot and the only thing left to do is get rid of them.
BTW, getting rid means throwing the whole filter out and getting a sand filter. As I understand it, cartridges aren't worth the money or the trouble.
 
I think you'll find a lot of people here love cartridge filters. I'm going to look at them if I ever need to replace my DE filter. You like what you like (& what you know).
I suspect since you have cartridge filter that you don't have a way to bypass the filter and simply recirculate the water. My concern is whether you have some other kind of blockage anywhere. But if you are getting good flow after cleaning the cartridges, then I'm going to assume that's not a problem.

How does the water look? Clear & blue? Murky and green? Cloudy & blue? Trying to ascertain whether you have an algae issue or not.
When you test your chemistry, was there any combined chlorine?
 

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Well, maybe the other cartridge-owners got a better break than I did. Abbreviating it a little, whenever I think I need to clean a cartridge, I have to take this ratchet to the nut on this big, heavy steel belt, removing it, then lift up the 4 cartridges individually, hold them up to let the water runoff, do whatever I need to do, put the cartridges back, wrap the steel belt around the filter again, tighten it, all the while banging on it w/a rubber mallet to make sure it's applying even pressure around the seal. Turning off the pump, moving a lever to "backwash" and turning the pump on again beats the pants off that routine! The last sand filter I had also had a recirculate feature, but I'll get to that later.
You're mostly right about not being able to recirculate. There is a air bleeder which can perform the same function, but I don't have the equipment to allow it to do that.
I think you're right about the non-blockage. If I was able to get good flow for that long a time at one point, then it seems the only blockage is the cartridges.
The water right now is a mess! It's not as cloudy as it was last week and a lot of whatever's at the bottom seems to have been removed, but it's still hard to really know, esp. at the deepend. I've been running a Kreepy Krauly, which just seems to get leaves in it when I bring it out (from a dappled willow. They're pretty small), and fewer and fewer of them.
No. No combined chlorine. There should be chlorine when I get that bleach into it tomorrow afternoon. By then, though, I hope to have what I need to make a decision about continuing to treat the cartridges or replace the whole filter.
 
The process you go through for pulling the carts is essentially the same as pulling my grids in a DE to do a deep clean. Like cartridges, it is really only meant to be a couple of times a year.

Sounds like there is still a lot of junk in the pool that the cartridges are catching.
 
The stuff at the bottom that you can’t see is the “junk” I’m referring to. If you still have a good bit of organics and algae, then it’s going to both consume a lot of chlorine and fill your filter. What is concerning to me is that a quad element filter like that should be able to take a lot of debris between cleanings. Not being a cartridge filter owner, I don’t know how to advise when to declare cartridges dead. In my limited experience with them, that’s usually when they start falling apart or letting stuff through. But I can see that maybe there comes a point where you can’t get them to fully clean.
 
Well whatever it is, it is both invisible and remains after running a hose over it.
I got a professional opinion, which is that my cartridges are shot, which is a pretty good explanation for the above. So I arranged to get a sand filter, which will set me back about 1000CAD after materials, labour and tax :cautious: It'll pay for itself in about 5 years or so
 
Hi and man you have had a couple of things going on that is for sure. It seems like the cloudy water + the saw dust was a 1 2 punch to your filter.

So the cloudy water=algae bloom starting. It is not full blown yet but it is not far off from being green.

What you need to do is find some liquid chlorine. Be very careful if you go for bleach. Do NOT get any with pretty smells or splashless or clormax as all of those have additives that will make things worse.

Get about 10 gallons of liquid chlorine.

Get Pool Math as seen here: PoolMath

Bookmark this link: SLAM Process as this is what you need to do to clear your pool water.

Oh and how are you testing your water?

Can you run your pump without the filters in it?
 
Oh, Cloromax is bad, is it? I bought 3 gallons of it, and each of them was around 5.50USD. It says "original" on it and doesn't brag about any pretty smells. You're sure it's wrong? 10 gallons sounds like a lot though. I bought 3 thinking I'd have leftovers for next time.
I test my water w/a TF-Pro. I can run the pump effectively for about 20 minutes. I did that when I increased the alkalinity.
 
Lets back up a second............................did you read the SLAM link I sent you? SLAM is a process for clearing your pool. It is not a one and done. The most important part of the SLAM is the M as in Maintain. You are to Maintain the FC level for your CYA until your pool is clear.

That is why I asked if you could run your filter without the cartridges as you have to keep the water moving to mix the chlorine in the water.

What you bought may cause some foaming so get some regular bleach or liquid chlorine. Can you take back the other stuff?
 
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Yeah, I'll save the receipt and get some more natural bleach.
My filter doesn't have a recirculate mode, but I suppose I could take out the cartridges. I'm not sure what the consequences are for operating it that way... for a filter I'm about to throw out (does a filter like this, w/out good cartridges have any salvage value?)
 
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