Air getting into filter system

Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
My pond has a Hozelock Bioforce Revolutions filter with a matching Ciprio pump installed about 8 years ago. The water from the underwater pump goes out through 40mm hose, exits the pond up a rise to where the filter is mostly buried. The top of the filter is about 2' above the water level. The 40mm hose from the filter re-enters the pond on the plant shelf about 6" under the surface, generating a visible current that the fish can be seen swimming against. Over the past few months there have been quite large amounts of air periodically coming out of the outflow pipe, and bubbling to the surface. There are no water leaks, and no loss of water from the pond. Both ends are underwater, so the air must be getting in via the filter. I can't work out why, or how, the air is getting drawn in. I would have thought that the water pressure would prevent this. Plus, if air can get in, why is no water getting out? I normally just use the Revolutions handle and waste pipe the keep the system clean, but I have just taken the filter apart for a more thorough clean, though it was surpringly clean anyway. Can anyone explain this to me please?
 

JRS

Joined
May 15, 2019
Messages
1,182
Reaction score
711
Location
Wisconsin
Showcase(s):
1
Hardiness Zone
5a
Country
United States
Welcome to the forum. No experience with that filter but some type of venturi effect comes to mind. Perhaps some air trapped at the high point in the filter box above the water level and the water flowing past sucks some it along as it returns to the pond. Or or perhaps a small crack or hole letting air get sucked in to the system.
 

j.w

I Love my Goldies
Joined
Feb 1, 2010
Messages
33,809
Reaction score
20,807
Location
Arlington, Washington
Showcase(s):
1
Hardiness Zone
USDA 8a
Country
United States
1652040283893.gif
and welcome @NigelW
Can't help ya on that filter problem.
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
Thank you both for the welcome. To clarify, the Revolutions filters have a handle on top that rotates paddles in the filter medium, whilst the outflow is temporarily switched to a waste pipe instead of the normal outflow to the pond. I normally just use this rather than opening up the filter. Given that the filter medium was quite clean, it seems to work well. The eruptions of air from the outflow pipe are quite volcanic, so I am hoping that someone will know why this has started happening!
 

mrsclem

mrsclem
Joined
Jul 21, 2008
Messages
5,490
Reaction score
4,959
Location
st. mary's county, md.
Hardiness Zone
7A
Country
United States
It sounds like the gasket on the lid to your filter may be letting air get sucked in. Have you opened the filter lately? Check to see that the gasket is clean and properly seated.
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
Thanks for the reply mrsclem. I did take it apart a couple of days ago to give it a proper clean. The lid has a rim that fits into a seal slot all the way around, and all secured with a substantial clamp. The water must come above that level to force the water out of the outlet, which is in the lid alongside the inlet. I am perplexed as to how air can get in without water getting out. The whole system is pressurised by the pump, and it is quite powerful as demonstrated by the current in the pond where the outlet returns. I am a bit suspicious of the valve that switches the flow to the waste pipe for cleaning, but I am reluctant to try to dismantle the lid and all the mechanisms in there!
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
I did replace the hoses last year. Given the water pressure, I think that a hole would be leaking water out, not letting air in. This is what perplexes me. When I changed the hoses, one of the unions with the filter was leaking. I did eventually fix that with PTFE tape. It is very strange - any sort of plumbing leak normally results in water getting out, not air getting in!
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
No, I have never opened it before - I have just used the revolving paddles to stir it up to get rid of the gunge. It has been fine for years, and the bubbling started in January. The pond was all netted over for winter, and I was only able to take the net off last week after the magnolia petals stopped dropping. I was hoping that a proper clean would fix it, but it didn't. It really didn't need cleaning anyway, but I do need to replace the UV bulb. Thanks for the suggestions. It is time for bed - 11.30 pm here in the UK!
 
Joined
Jul 12, 2009
Messages
3,990
Reaction score
2,696
Location
Mount Pocono, Pennsylvania
Hardiness Zone
6a
Very strange that nothing is leaking but air is getting in.

I would take a look at that union that you patched up, maybe change it. I wouldnt trust any type of tape considering all that water pressure.

This is a long shot....
Did you try turning it off and then looking for a water leak? Maybe without the pressure of the pump the leak will be more evident?
Just a wild guess...
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
Thanks to everyone for the suggestions. The problem is that there is no way of seeing what is happening inside the system in operation! All the hoses connect to the lid. The water coming in through the inlet is supposed to sprinkle down through holes in the plastic baseplate of the lid, go down through the filter mediums, back up through a central tube past the UV lamp, and back out through the outlet. The outlet to the pond can be switched to a waste outlet to flush out dirt whilst a handle on top turns internal paddles to agitate the filter sponges. It seems very unlikely that there would be no sediment in the filter when I opened it up last week, and I suspect that something has gone wrong inside the lid, such that the water is not actually going down through the filter medium. This could also explain where air is getting in.
I have put in a support request enquiry to the manufacturer, but they may take a week to reply, and may not have the answer. I hope I don't have to buy a new filter as they cost £250/$300.
In the meantime I am open to ideas!
 
Joined
May 8, 2022
Messages
10
Reaction score
2
Country
United Kingdom
Are you sure this patch with tape is not the culprit?
For the low cost of a union, I wouldn't chance it. I would replace it.
The flexible hose is the type with the spiral wire, and it slides directly on the the filter inlet. It was dripping all the time, no matter how tight I clamped it. I wrapped the inlet with PTFE tape before sliding on the hose, and then tightened the clamp. That stopped the drip. PTFE is plumber's tape, and used in the trade to help fill the threads on screw joints.
This was the inlet to the filter, and under the highest pressure. I am confident that there is no air getting in there.
 

Ask a Question

Want to reply to this thread or ask your own question?

You'll need to choose a username for the site, which only take a couple of moments. After that, you can post your question and our members will help you out.

Ask a Question

Members online

No members online now.

Forum statistics

Threads
31,488
Messages
517,713
Members
13,688
Latest member
Dana D

Latest Threads

Top