Excess air in filter basket

[billbrach]

Hello,

I have an older Leisure Bay 320 gallon, 5 person hot tub, about 12 years old.  The only work thats ever been done on it was to replace the 24 hour circulator pump, about 8 months ago, and remove the failed ozonator assembly.  Everything else has performed flawlessly, considering the age of the unit.

A new problem has cropped up, and I'm not sure where to look for the problem.  This spa has a standard, top-load filter basket assembly, that uses the large, approx 4" x 13" pleated filter.

What is happening, over 24 hours, is the filter basket is filling up with air.  If you let it run with just the circulator pump running, the basket will fill 80% or more with air, effectively reducing the filter to the lower 2".

Question is, is there a likely place for air to get into the system ?? A cracked fitting ??  I have the control box side of the housing open, but the filter basket is in the right right corner, and cannot be seen from the front.  I can remove the side panel, and look but I'm trying to narrow down the problem.

Additional information: I removed the ozonator months ago, when I replaced the circulator pump, and plugged the hose feeding into the spa.  I've unplugged that hose, with no difference; the filter basket continues to fill slowly with air.  Additionally, I removed the top to the filter basket, and the filter, and then turned the spa back on, and I see occasional air bubbles coming up from the bottom, inside of the basket, in the water flow.

Thanks for any help in this matter !!

Bill

[Vinny]

Is it a sealed system? It sounds like it is. Most tubs use a weir and they are open to the tub for the most part.

Any water leaks? If you were to turn the pump off (tub off) - are there signs of water leaks? Does the pump suck water from any place else?

Those bubbles you see may be an indication ... anything looks cracked. Did you look under the filter to see if you see anything?

[Tman122]

Is it at the proper water level?

[billbrach]

Thanks for the suggestions.  Water level about 1 inch above the mark.  It's been here for a long time, and I don't think that is the issue.  As far as I know, no water leaks either, as the level is not going down.

There is a small jet at the rear of the tub, that the water from the 24 hour circulator pump comes out of.  This stream has way more air bubbles than normal.  I'm guessing there is some sort of venturi or air-injection device, and that that might be where the problem is.  Unfortunately, the tub is sitting inside a 3 wall, 6' high enclosure, and it will have to be disassembled to get to that side of the tub.  I can get to the basket filter side w/o too much trouble, so will look there first.

Currently, I'm leaving the bleeder valve on top of the filter basket, slightly cracked, to continuously purge the air, but I'm sure that is reducing my filter efficiency.

Again, thanks for the suggestions.

[Vinny]

How old is the filter? If you just bought a new one - not all filters are created equal. I am finding it hard to visualize your filter setup - If it is a sealed filter like a house water filter (top and bottom) I guess it's possible that the water on one side of the filter is more than the other (taking into account the obvious that the tub is full of water!  , the center of the filter may not be getting enough water going through the filter to cause that. Can you look into the filter center and is that what your seeing - less water on the inside of the filter than outside? Or is the whole water filter losing housing water? You mention losing efficiency - is the system pressurized like a pool filter? I wonder if you have a clog from wherever it sucks water to the filter housing.

The venturi should be after the filter, it should go something like: tub water -> filter -> circ pump -> venturi -> back into the tub. Any excess air from the venturi shouldn't be going into the filter.

Sorry, I can't be much more help. I can visualize my pool filter and it only gets air in the filter when it sucks in air before it - could be from low water level or whatever and then I bleed the air out and I'm good to go until the next time it sucks in air. My spa filter just has a weir gate which swings in to accommodate the circ pump sucking in water through the filter.

[Tman122]

Check your ozonater venturi.

[billbrach]

Filter looks like this one: http://www.hottubworks.com/part-2-502-2510-item-hottub-filter-assembly.php

It is mounted below the top surface of the tub, down in a well, in one of the rear corners.

The ozonator venturi sure seems like a place to look, as there is way more air coming out the venturi/24 hour circulator pump jet than there is supposed to be.  Unfortunately, to get to that, means removing the walls of the protective enclosure I built around the tub.  Might be a few weekends, until I can get to that.

Again, thanks for all the suggestions.  Once I find the problem, I'll report back to the forum

Bill

[Tman122]

With an older tub I would I modify my access to the equipment bay. You may need it more.

[billbrach]

I finally found the problem.  There is a hard white plastic tubethat runs up the inner sidewall of the filter basket, to the top of the filter basket.  Although it looked clear, it was plugged down at the bottom with what look like bits of bugs and dirt.  I guess that tube acted like a mini-skimmer in the filter basket, sucking stuff down it that it should not.  I'd insert an image but cannot figure out how to do that.

[Vinny]

Glad you figured it out!