Pond Boss
Posted By: timberpond HiBlow aeration issues - 09/06/21 01:35 PM
Hello all,

This is my first post here. I am hoping to get some advice on aeration with some issues I'm having.

I have a very shallow pond, max 3 feet deep that is just under one acre. I tried the following setup:

Hiblow120LL pump.
1/2 pex 'T' splitting the output with two valves at the pump and two 1/2" pex lines buried a couple inches underground to the pond edge.
90' 1/2 weighted line to one matala 9" diffuser and 110 feet 1/2" weighted line to another matala 9" diffuser. The diffusers are about 20 feet apart.
Diffuser heads are about 2 feet deep.

I can turn the pump on and adjust the valves so both diffusers are getting about the same supply of air, but honestly the air coming out seems less than what i expected watching other videos. After about an hour, one of the diffusers will completely stop emitting air and the other seems to have much less flow.

Just as an experiment i took the diffuser head completely off one side and turned the other off, and the pump seems to be sending plenty of air (to the 110 foot run) and has been for several days straight. It almost seems like there is not enough pressure to push the air through the matala diffusers.

I wondered if anyone could give me any tips on what I might be doing wrong. Is it the pex T valve? The Pex all together? The length of the weighted tube runs? Should i get diffusers with larger openings? Should i just run one diffuser?

Thanks in advance for any advice you can provide!
Posted By: Quarter Acre Re: HiBlow aeration issues - 09/07/21 12:32 PM
It could be a combination of things. I am going to suspect the 1/2" line size, first off. But, it could be that the fittings and valves you are using. If the fittings and valves have much smaller passages, they could be restricting the air flow at the fittings themselves. By the nature of flexible plumbing, fittings for specific line sizes have smaller passages...some more than others.

It's possible that the lines are getting water in them and that water is harder to push than air, or harder to push air around it. It's very hard to push water through a diffuser membrane too. Do your diffusers have check valves in them? Any leaks in the lines?

Once the system has been running a while and one diffuser dies back...it's possible that the pump is getting hot and dropping capacity. I'm not too familiar with diaphragm pumps, but it's something to look into. Do you have a pressure gage so you can see if the pressure changes as the air flow changes? The pressure should change as the air flow weakens so long as the pump is working properly and it may be exceeding the pumps capabilities.

The HB120 should be more than enough pump to run two Matala's at those shallow depths. I'm thinking line and fitting restrictions or it's getting water in the system. Aside from the problem you are having with the base system...I am wondering if 2 diffusers is adequate for your pond size, however. I say this because I am sure we can get the two diffuser system working better, but will it be enough to properly turn all the pond water over so that aeration benefits are achieved?

Welcome to PB!
Posted By: timberpond Re: HiBlow aeration issues - 09/07/21 03:31 PM
Thanks for the response! I'm going to try and simplify the system by running a single 3/4" poly pipe to the water's edge and a matala manifold 3/4" input with two 1/2" outputs and will add a pressure gauge at the pump. The only place water could be leaking into the system will be where the pipes connect to the diffusers.

I did not add any check valves after reading that the membrane type diffuser acts as a check valve when not running.

This is a pretty old pond (probably 50 years) and is fed mainly by rainwater. I'm not sure if there is a spring at all. I am mainly trying to help stagnation issues and prevent fish kills. I know 2 diffusers may not be enough but I just want to try to get some water movement and then i can always make adjustments later.
Posted By: timberpond Re: HiBlow aeration issues - 09/12/21 11:35 PM
Well I put a 3/4" irrigation line to a manifold and added a 0-15 psi gauge. When i turn on the pump, even when the manifold valves are closed, the reading on the gauge is zero and doesn budge. I can blow straight into the gauge and it works. When i take the manifold off the hose is blowing air.
I just don't understand it.
Posted By: Bill Cody Re: HiBlow aeration issues - 09/13/21 12:25 AM
Do you have a picture of the pump, manifold, gauge and hose - entire assembly.
Posted By: esshup Re: HiBlow aeration issues - 09/13/21 02:49 AM
Sounds like the pump isn't pumping air. Is it new or old? How old?

How many feet of water are over the top of the diffusers?
Posted By: timberpond Re: HiBlow aeration issues - 09/13/21 11:55 AM
Hi,

I have attached pics. It is a new pump two months ago and over the past few weeks have just been trying to set it up. The diffusers are about 2 feet deep. The pond is about 3 feet deep.

The pump is pumping air. I am not familiar with these type pumps so I am not sure how much 'force' the pump should be emitting air with. I can say that i can easily hold my hand against the outlet and it doesn't take much effort to stop the flow but I assume that is the way it's supposed to be.

It is very frustrating because it seems like this should have been a fairly simple project that is turning out much more difficult!
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Posted By: esshup Re: HiBlow aeration issues - 09/13/21 02:14 PM
Unfortunately, with water that is that shallow, aeration won't add much more (if any) O2 to the water than what is already there.
Posted By: timberpond Re: HiBlow aeration issues - 09/13/21 03:06 PM
Thanks. I understand that it isn't the best situation, but i am really trying to break the surface of the water. I hope to eventually be able to have the pond dredged a couple feet as well. I'm currently just trying to get this pump going. I wonder if it is a problem with the pump itself? i know there are no leaks in my line going to the water's edge.
Posted By: esshup Re: HiBlow aeration issues - 09/13/21 05:32 PM
Take the airline off that fitting that goes to the pond. Turn pump on, put hand over where the airline was. If the pump doesn't build pressure (as shown on the gauge), the pump is toast.
Posted By: Quarter Acre Re: HiBlow aeration issues - 09/13/21 07:39 PM
If the pump is in good working condition, you should see 6-7 psi (maybe a bit more) on the gage when you do what essup suggested above.
Posted By: Bill Cody Re: HiBlow aeration issues - 09/14/21 01:00 AM
All piping and connections look okay. although I don't like the manifold. I prefer adjustable ball valves on the manifold to precisely regulate and distribute the air flow. Good advice from esshup and 1/4ac. If the pump does not create 4-5psi then it is a pump problem. Take the top off and see if there is an air leak somewhere or loose screw of a fitting. Maybe the diaphragm is cracked? As long as the pump is humming the diaphragm is maybe cracked or damaged. They sell rebuild kits that include a new diaphragm for that pump.
Posted By: timberpond Re: HiBlow aeration issues - 09/14/21 03:27 PM
Well I found the problem! At some point one of the mounting blocks sheared off. I assume during shipping. Thanks everyone for helping and I will give everyone an update when I get up and running!

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Posted By: esshup Re: HiBlow aeration issues - 09/14/21 07:48 PM
That will do it! Thanks for the update.
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