New Intex sand filter - too much aiir while vacuuming?

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CeltiaK

CeltiaK

0
Bronze Supporter
May 8, 2014
35
Western Mass.
Hi folks,

I have read a ton, but I haven't really seen my specific situation come up, so here goes.

Background first: Last year, we bought an 18x48 Intex inflatable. I was TFPC from day 1 and we never had any major issue. Minor issues were all side effects of the small pump and filter - overloaded pollen, cloudy water from lots of sunscreen, lots of bugs on surface, etc. But pool health was always good, and we never had chlorine demand problems. I cleaned the filter 2-4 times/week, vacuumed 1-2 times/week, and skimmed the surface daily.

This year, right away, we upgraded to the 2800 gph sand filter. The difference is already remarkable. I thought we had a nice sparkly pool last year, but this year our sparkles are RAINBOW sparkles. It's really amazing. Mesmerizing, in fact. But I'm having a few new issues and I'm not sure if I actually have a problem, or if this is a new normal.

The sand was purchased at a pool store - Mystic II angular filter sand. It's very white, and while I'm sure I didn't backwash or rinse long enough, I don't think I've had any sand go back into the pool. So that's one problem I don't have.

What I do have is a lot of fine silty brown dust? pollen? dirt? on the pool floor. We're suffocating under crazy pollen right now in New England, and I live near lots of farms. Either the silt on the bottom is dirt I didn't wash out of my filter, or it's pollen and farm dust. We've been in a couple times, and it just dissipates with turbulence. Currently, it's too cold to collect some and look at it under my daughter's microscope. I know I have to vacuum, brush, keep the pump running, keep a cover on, and possibly add DE to my filter. I had hoped it would just go away, but it's been 2 weeks and the dust is still there (with pump on 4 hours/day). My FC has not dropped below 4 ppm since opening (CYA currently targeted for 70), so I'm reasonably sure it's not algae (I never have CC when testing). My pressure gauge started around 8 psig and it's still there. I haven't backwashed since my initial startup. Am I correct that I just need to keep cleaning and the dust will probably get better when the pollen dies down or the sand gets a little dirtier? Am I missing something?

My next problem is the air in my prefilter when I vacuum. With the old pump, I was used to bleeding out the air in the filter whenever I saw bubbles at the return jet. If that didn't fix it, I knew it was time to clean the cartridge filter. With this new sand pump, I can't bleed air out, but it seems to take care of air on its own. But the new pump is so powerful, it creates a suction side vacuum whenever I hook anything up to the nozzle. I have an over the wall skimmer that kind of works, but I can only use it when I'm able to watch it - otherwise, it clogs or starts to float, or the nozzle strainer grid clogs and I have to detach the skimmer from the wall to clear the grid. If I have to watch it, I might as well just skim manually.

Vacuuming is equally trying. It's a cheap pool, so I picked up a cheap Intex vacuum - why mess with nonstandard connections if I don't have to? As soon as I connect the (fully primed and correctly submerged) vacuum, the prefilter floods with air and the water level drops to about halfway. Is that normal? Am I causing damage to the pump? Is there any way to fix it?

Frankly, I've about had it with that suction nozzle strainer grid. I'm ready to cut it right out and rely on the prefilter to catch the big stuff. Is that a good idea or a horrible idea? I did see a post recently where some others cut theirs.

Sorry for the novel. I have been reading, reading, reading, but I guess I let my problems pile up a bit. Thanks for any help you can offer!
 
Welcome to TFP!

Your description of the brown dust sounds an awful lot like barely controlled algae. That's exactly what you see. But it could be from a high debris load.

Chances are your pump is just moving too much water to be fed by only the water coming through the hose. It's starving for water. What you need is a method to allow the pump to draw some water directly from the skimmer and the rest through the hose.
 
Interesting. Guess I'll do an OCLT tonight.

Here are last Saturday's numbers from my 1-year-old TF100:

Temp = 69
pH = 7.2 - Added 14 oz. Borax to bring back to 7.5
FC = 4.5
CC = 0
TA = 90
CH = 75
CYA = 50-55 (That was my initial addition, targeted 50)
Salt = 2650 (Still need to buy 1 more bag, but no rush)

This week I added more CYA to target 70, which is where I'll keep it all summer. Next week, I'll get the rest of the salt in. Currently running the SWG 3 hours/day.

This week, pH rose a bit, then fell a bit due to CYA:
7.5, 7.6, 7.6, 7.5, 7.4 today

TC is rock solid:
4, 4, 4, 4, 4 today

I did manage to fix one problem. I put a rock in the skimmer basket. It ran for 2 hours with no problems.

How would I add water while vacuuming? The skimmer gets disconnected for vacuuming. I really think I need to hack off that strainer grid. It's got to be reducing throughput.
 
It sounds like fine silty dirt on the floor of your pool. I get it too. Even if you vacuum it all up, unless you keep the pool covered, it will be back in a couple of days.

These Intex pools don't get enough circulation at the lowest level to keep all the dirt stirred up so that it gets filtered out, especially if you're using an over the wall skimmer. You can try to angle your return eyeball downward more to help stir up the bottom, but you'll still have to vacuum regularly to keep it totally clean.

I hit mine a couple of times per week. Adding some DE to your sand filter might help it remove the finer particles more efficiently. Don't start with too much, maybe 1/4 cup, or your filter pressure will spike and the flow will drop, further reducing circulation.
 
I cut my suction and return strainer grids out and it made quite a difference in flow.

my pool would get the "dust" also. I made a system to temporarily reroute my return water through a 1micron filter bag. When we would vacuum the pool, the ultra fine particulates would travel through the filter. Once before we knew about CYA, the algae took over. When my wife spent over an hour vacuuming the pool, she noticed the algae was going through the filter and back into the pool. Once I added the filter bag, all my water clarity issues went away. I put the bag on when I vacuum and leave it one for a few hours afterward. Our water sparkles like a glass of Perrier. Huge difference.
 
Thanks everyone. I did an OCLT last night and I don't think it's algae. I did find something interesting though!
10 pm: FC = 6.5, CC = 0.5, pH = 7.4
8 am: FC = 6.5, CC = 0

So no loss - that's good. But that's a really high FC! For me, at least. Here's my theory... For 2 weeks, I've been battling the dust at the bottom, but I've only been vacuuming every 3 days or so. I was manually skimming multiple times a day, and keeping the cover on at night. The top of the cover was a crusty yellow mess. Thursday (2 days ago), I cleaned the cover, vacuumed, and skimmed. As soon as the pump shut off, I covered the pool. Friday, I vacuumed and figured out a way to keep the surface skimmer running. The cover went back on early afternoon due to cool temps and a lot of wind.

I think my stable FC was actually just keeping up with holding pollen and bugs under control. If we'd been using the pool, it would have been harder to keep up. The current high numbers are telling me I did a good job cleaning and there's nothing left to consume the chlorine. I'm going to vacuum again today - there's almost no silt left - and maybe dial back the SWG until it warms up later this week. And I'll plan to vacuum every 2 days until the trees and pollen let up!

I think I will try the DE - I really love how clear the water is this year. When the surface is still, it looks like it's only 2 feet deep and there's no water in there! Until you see the dust in the wrinkles. Bah.

And Jeff, thanks for the tip about angling the return toward the bottom. I've always kept it to the side to promote circulation, but this might work. The new pump has some oomph!, and I feel like I learn something new about it each day.

Gtty - how did you cut out the grid? Did you remove the valve or is there a way to cut it in the pool?
 
I also have the air problem. Pretty sure it is cause by a relief valve that is located on the water inlet and outlet valves. They look like little knobs with no apparent use. Their purpose is kid safety, allowing suction that could trap a child to be relieved.

On my pool with a skimmer, there is no suction danger. I am thinking of sealing the relief valve on the suction side with RTV so I can have full vacuum power. As designed, the relief valve making the vacuum so weak as to be practically useless.
 
I had the air in the pump basket when I used a section side cleaner. I have a Hayward pump and it was never enough air to cause a problem...until it was. After about a year, I hooked up the cleaner and I could not get the air out of the system long enough to get the vacuum to run. I was also getting tired of having to deal with it in general so, I sold it and bought a robot. No more problems.
 
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