Pond Boss Forums GENERAL QUESTIONS Property Projects & Construction New pond owner, lots of questions

I web searched for the "matala 4 pro" and got this hit...

http://www.matalausa.com/MEA-PRO-4-PLUS-KIT/MEA-PRO-4-PLUS-KIT-p-277.html

It says your kit uses the "Matala HK60L Air Pump". So I searched on that and found that the Matala and the Hakko must share the same pump. Here is the site with the pump data that I ASSUME you have (it looks the same anyhow and has the same HK60L numbers)...

https://www.hakkoairpumps.com/subcat9.html

And the curve copied from the above site...



With your diffusers being around 5 foot deep, your pump should be putting out just over 2 CFM. This is a good CFM for 2 of the common diffusers. What I can not find is how much water can be moved by these diffusers at that CFM. Two other things concern me about the systems. 1.) The first noted site says the 4 pro system is "For Ponds between 8000 to 20,000 gallons.", AND, the second noted site says the assumed pump is "Suitable for koi ponds up to 6000 gallons.". Neither of these specs suggest it is sized appropriately for your pond size.

Using the below pond calculator...

https://www.pondvolumecalculator.com/

...with a 60'x100x pond with an average depth of 4'...It calculates 180,000 gallons. Lets' say that this number is off by 50%, for discussion's sake, that is still 70,000 gallons larger than the largest spec for your system. What this is telling me is that your pond may not be turned over at a rate that is good for adding good dissolved oxygen to your pond for good fish health. A good rule of thumb is to turn your pond over at least once a day (I prefer twice or more for good measure). I don't think you can turn it over too much unless turbulence becomes an issue and that would take A LOT of aeration). What is mostly happening with an aeration system is that the water is being moved upward, from the bottom, so that it comes in contact with the air and can absorb oxygen. The bubbles do very little with respect to adding O2 to the water. It is the water to air interface that does the majority of the O2 transfer to the water.

If you can get the water-lift-rate from Matala on these specific diffusers (at 1 CFM each)...we could do further calculations to determine if they are moving enough water to properly aerate the pond.

Ok, that's all the mumbo-jumbo I can spew out regarding your system, BUT, I think we can try a test to see what's really going on in the pond. The following test may have some inadequacies depending on several factors, but it is a start to understanding your pond and aeration system.

Most ponds will be cooler at the bottom and warmer at the top (without aeration and during the summer months). With smaller/shallower ponds like yours, I would think this statement would better apply at the end of a hot day. So, it might be helpful to know what the temps are near the top and at the very bottom at the end of a hot day (not necessarily sunny). I would get a cheap pool thermometer, tie something heavy enough to make it sink, tie that to long cord with a float (like a plastic soda bottle), set the float so that the thermometer will be at 18" below the surface, and throw it out into the middle of the pond away from the diffusers for a few minutes and pull it in quickly. Record the temp. Now, take the float off and throw it out to the bottom (away from the diffusers but very near the deepest part) for a few and pull it back in. Record the temp.

If the temps are within a few degrees, your aeration is turning the pond over enough to mostly mix the water and maintain a fairly constant temp top-to-bottom. Be aware that water at the very top will always be warmer than that just a foot down or so. That is why I suggested 18" from the surface for the the top temp an not necessarily a sunny day.

Knowing what these temps are without aeration would also be nice to know for comparison, but that involves shutting the system off for several days to let it settle down and repeating the temp readings. Keep in mind that starting a system back up needs to be done gradually to avoid killing any fish in the pond.

My 1/4 acre pond (10 foot deep) can have a 20-30 degree temp difference from the bottom to 18" below the surface without aeration, but with aeration, that temp difference is more like 3 degrees. I have taken multiple temp readings at 6" increments, top-to-bottom, to find where that breaking point is. The breaking point is where the effects of the sun stops heating the surface water. My pond is pretty muddy which makes that point closer to the surface whereas a pond with more clear water and less aeration may be further down.