Losing Prime after 5min

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This is a thread I started about cleaning a Pentair QUAD filter and it has pictures -


Thread 'Guts of QuadDE Filter'

Guts of QuadDE Filter

Sadly, some of the pictures are broken because that thread came from the old days when I used Photobucket a lot.
 
Have you performed an overnight chlorine loss test (OCLT)? Perhaps you have an algae bloom starting? A nascent algae bloom will plug up a DE filter way before the algae starts to become visible.

I have a QuadDE 100 on my 16,000 gallon pool. I typically only clean it out twice per year. I never backwash.
 
JoyfulNoise said:
Have you performed an overnight chlorine loss test (OCLT)? Perhaps you have an algae bloom starting? A nascent algae bloom will plug up a DE filter way before the algae starts to become visible.

I have a QuadDE 100 on my 16,000 gallon pool. I typically only clean it out twice per year. I never backwash.
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I did do an OCLT a while ago. No loss. As for algae, yes absolutely. But it doesn't bloom until my IC40 stops working due to low flow. By the time I realize it is reading low-flow the pool is already green. Again, it turns fast due to palm trees that absolutely litter my pool this time of year.

So not sure if it is low-level algae that suddenly takes off or if the IC40 low flow causing a drop in Cl that allows the bloom.

Thanks for link - I will read through it to see if there is anything that I can change on how I clean my filter. I generally don't backwash either.
 
Chad1979 said:
How often are you checking your CL? It almost sounds like your pool system and swcg are on the flirting edge of algae blooms and when the system flow gets too low you have a bloom happening. What are your test numbers?
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I'm not the best and I admit that it many times is not good. But this seems to be a flow problem more than an algae/chemistry problem. I'll explain more below.
Mike1162 said:
It's not making sense to me that flow is decreasing but you're not seeing an increase on the pressure gauge. Could the gauge be faulty?
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I'm assuming you mean the filter pressure gauge?

As I said above, I cleaned the filter out on 7/2. Pressure went to a normal and the flow was good. I started SLAMing and today, just now, 7/4 at noon, the flow is already low. It literally was flowing fine when I got in and within 30mins it went low flow. The pressure gauge did not suddenly jump up - just the flow suddenly dropped.

I cleaned the skimmer (not bad). I cleaned off the floor port (had some stuff on it, but not blocking it). I cleaned the pump basket (some stuff on it, but not bad). Turned pump back on and pump pretty much instantly primed and went back to normal flow. Then about 30sec later it went to low flow on the IC40. FlowVis reads 20gpm. This is at 2200rpm.

And before anyone says it - yes the careful chemical levels I am sure do not help stop algae which in turn clogs the filters. But in this case I just cleaned them less than 48hrs ago. If I kick it up to 2900rpm then I have IC40 good flow again.

I took some numbers a year ago as I was trying to find out how often to clean the filters:
Filter with no DE, 1610rpm, 0psi, 40gpm
Filter with no DE, 2500rpm, 9psi, 60gpm
Filter with DE, 1610rpm, 0psi, 40gpm*
Filter with DE, 2500rpm, 9psi, 60gpm*
* These numbers dont make sense as I would expect a flow decrease and a pressure increase with DE charged

Then just 2 months ago when I started having issues, on old filter grids:
Valve on circulate (bypassing filter), 1900rpm, 35gpm

Just tested again at 2000rpm, recirculate and it is at 40gpm. If I turn it back to filter then it will go back up read OK on IC40 , flow of about 30gpm and if I sit there for X minutes (could be 5min or 15 or 120) the flow will eventually go down to about 18-20gpm and the IC40 will turn off.

EDIT: I just now turned it to 2900rpm as that was allowing the IC40 to work but now it is back down to 20gpm and IC40 low-flow. So I'm basically back to where I was prior to replacing the grids. Guess I can tear down the filter yet again and get ya'll a baseline of current pressure and flow with a freshly cleaned filter.
 
You say you are doing a slam? If so, you are killing a lot of algae. From what others state filters clog very quickly during a slam as the algae is dead and getting scrubbed off the walls and floors and other parts of the pool and stirred up in the water so it is getting pulled into the filter. That in itself is going to fill up your filter. Now im not saying you dont have a flow problem that may be mechanical, but i think your filter is getting plugged with dead algae.

Just a few questions. When you have low flow or problems with your swcg not working due to flow, does your pump motor sound differently at the same rpm than before? Do you watch your pressure gauge when filter is clean and you have good flow vs when there is no flow/ filter dirty? When the pump is turned off, does the gauge read zero? Does your flowvis show zero as well when pump is off?
 
Just woke up and pool is on auto schedule. 2900rpm, 21psi, 45gpm. So it is acting like nothing is wrong.

I'm still going to tear it down and get a good baseline...
 

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Mike1162 said:
Can you put the bladder in the pipe that goes to the skimmer but put it in at the filter end?
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I have a water bladder but I'm not sure what you mean. I think you mean my test #6 on my first post? If so I haven't done any of these bladder tests since April. I essentially quit doing them because when I go to bypass/recirculate and bypass the filter the flow is normal. If I stick my hand in the skimmer then the draw is very strong. Which just confuses the matter more, but seems to suggest that the return line from the pool to the pump is not clogged.
 
peacefulkancer said:
Just woke up and pool is on auto schedule. 2900rpm, 21psi, 45gpm. So it is acting like nothing is wrong.

I'm still going to tear it down and get a good baseline...
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Tore it all down again, including the IC40.

2200rpm, 40gpm, 10psi, IC40 reads good flow.

The grids were not that dirty. IC40 did not have a lot of buildup (water is super hard here). Water and chemistry is a mess as it has been storming here in Phoenix (odd, I know) and my chemistry was not good to start with. I'll get some readings later today or tomorrow.

Do have a bit of a conflict in my mind though on how much DE to use. Quad DE 80 says 8lbs. My original method was to use a plastic cup that I had measured out the weight in and just multiplied that by how much I needed (i.e. each cup held 0.4lb so 18 cups worth to make 8lb). Then I got one of those DE cups and says 1 cup per 5sqft so added 16cups. This time I actually weighed it out in a bucket and I would say that the weighed amount was way way less than the blue DE cup method but similar to my original method.
 
To further confuse things, DE was originally measured with a 1 pound coffee can, so a pound of DE didn't actually weigh a pound. It was based on the volume of the 1 lb coffee can. DE scoops you get from the pool store are supposed to match the volume of the 1 pound coffee can.
 
If you are going by actual weight for your DE use, then you are adding way too much. If you use any cup other than a cup designed for DE then you will incorrectly add DE to your system. That blue DE cup you have should be the cup you use to add DE to your system after a full teardown or after a backwash recharge. I just seen a thread about DE a couple weeks ago and that was quite interesting to read and learn about. If i can find it i will link that thread here.
 
I've always weighed the DE and don't rely on coffee can methods. I would put an amp probe on the pump wire and see if there are different amperage readings on this throughout this up and down journey or even is the pump not upto par when all is clean just about squeaking by.
 
Chad1979 said:
If you are going by actual weight for your DE use, then you are adding way too much. If you use any cup other than a cup designed for DE then you will incorrectly add DE to your system. That blue DE cup you have should be the cup you use to add DE to your system after a full teardown or after a backwash recharge. I just seen a thread about DE a couple weeks ago and that was quite interesting to read and learn about. If i can find it i will link that thread here.
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If I weigh the DE then I use about 0.80 of a 5-gallon bucket. If I use the blue scoop as I linked previously then I use 1.5 5-gallon buckets. The math isn't adding up here.
zea3 said:
To further confuse things, DE was originally measured with a 1 pound coffee can, so a pound of DE didn't actually weigh a pound. It was based on the volume of the 1 lb coffee can. DE scoops you get from the pool store are supposed to match the volume of the 1 pound coffee can.
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Yeah I get that. And I guess I'm going by the manual (or filter label) that says "Quad DE 80, 80 sq, 8lbs." So I did 8lbs weighed out. I'm not sure how to interpret the manual any other way to be honest.
wireform said:
I've always weighed the DE and don't rely on coffee can methods. I would put an amp probe on the pump wire and see if there are different amperage readings on this throughout this up and down journey or even is the pump not upto par when all is clean just about squeaking by.
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I can do this, but... what would be my standard to measure against? Pump is new as of 2018.

RE: DE. So some are saying weight it. Others say to use the "special scoop." But the amount added is VASTLY different. So what is the answer?
 
I dont know the correct answer as it seems the manufacturers of the filters say something different than those that package the DE. From what ive read on different threads about DE is that there are different ways to do this, but not sure which is the correct way of doing it. Then again, maybe there isnt a correct way?
 
My manual says to mix X 1lb coffee cans according to the table which each can equals 0.5lbs. In the table a quad 80 is listed as 16 1lb coffee cans or 8.0lbs.
 
peacefulkancer said:
If I weigh the DE then I use about 0.80 of a 5-gallon bucket. If I use the blue scoop as I linked previously then I use 1.5 5-gallon buckets. The math isn't adding up here.

Yeah I get that. And I guess I'm going by the manual (or filter label) that says "Quad DE 80, 80 sq, 8lbs." So I did 8lbs weighed out. I'm not sure how to interpret the manual any other way to be honest.

I can do this, but... what would be my standard to measure against? Pump is new as of 2018.

RE: DE. So some are saying weight it. Others say to use the "special scoop." But the amount added is VASTLY different. So what is the answer?
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I would just start now and log what's happening. You may see a trend that ends guessing.
DE, I've always weighed my go to scoop vessel and depending which one is at hand. One is 1lb and the second is 1.5lb. I use weight and has always worked for me.
 

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