Dawn Fish Kills
When the weather gets warm, the changes are even more dramatic and deadly dissolved oxygen depletion occurs in late evening and early morning in portions of all non-aerated ponds.
Aeration for just a few hours on sunny or windy days does not stop dissolved oxygen depletion in ponds!
However, in PEC aerated ponds, our 24/7, solar powered aerators, prevent deadly dissolved oxygen depletion in the late evening and early morning hours.
HOW MUCH DO I NEED?
Simply stated, for recreational ponds, you need 1 cubic foot per minute of diffused air per surface acre at 3-10 foot of water depth. Deeper water requires less air to get higher oxygen transfer rates, but also requires alot of power and maintenance. More power means more and larger solar panels and higher capital cost. Risers and floating diffusers keep the bubbles off the bottom of the pond reducing power and oxygen demand while increasing water clarity and air flow.
OXYGEN DISPERSION & MIXING
High concentrations of dissolved oxygen around a diffuser quickly spread throughout the unobstructed pond. Bubblers require no additional energy to disperse the oxygen throughout a pond. If destratification in deeper ponds is needed you can deploy floating draft tube diffusers to destratify the pond while using the same energy needed for oxygen transfer while avoiding suspending bottom sediment and increasing turbidity in the pond.
Oxygen is continuously being produced
by algae and other aquatic plants where the sunlight can penetrate in all small recreational ponds. Without wave action, the oxygen levels near the surface of the water are often at and above 100% saturation throughout the day. Even a tiny amount of mixing energy (less than 50 watts/acre) can redistribute this supersaturated dissolved oxygen throughout the pond. This turns your pond into a massive oxygen storage tank, instead of allowing the excess oxygen to escape or "gas off" from the pond to the atmosphere.
That's where free energy and our Solar Powered Aerators come into play!
MIXING WITH DIFFUSED AIR
(the only sure way to under aerate is to turn off the bubbler)
Once you have added enough air bubbles to get the oxygen you need into the pond, you will never need additional energy . The power needed to transfer the oxygen to the water is many times what you need to disperse it completely through any contiguous body of water. It is a common practice in sewage lagoons and holding ponds to use less than 50 watts per surface acre of solar power to completely mix contiguous bodies of water.
As long as you do not disturb the bottom sediment, the deeper you aerate or draw water from the bottom pond layers, the better the oxygen transfer. For each 1 foot of diffuser depth you increase the oxygen transfer by 1-2% while doubling the capital and maintenance costs. As you try to aerate below 10 feet the technology changes to high pressure, high maintenance, lubricated air compressors which can become a daily maintenance headache. But there is another way to do it! You can aerate at any pond depth by partially submerging air diffusers or by floating diffusers inside tubes that reach down to draw the bottom water up to the top of the pond. Floating diffusers inside a tube pulls water from the bottom and pushes it out the top of the tube. This is often refered to as an anchored airlift aerator or draft tube. Proper sizing using either fixed bottom mounted tubes or floating bottom anchored diffuser tubes reduces costs by sacrificing less than 10% of the oxygen transfer efficiency and eliminating power bills. Draft tubes are a low cost method of preventing massive fishkills by creating large safe zones of oxygen rich water.
Non-recreational and sewage lagoon studies using diffused air, mechanical surface aerators, and fountain mixing energy based on shallow 6-20 ft deep were designed to keep sediment (light solids) in suspension while providing very high levels of oxygen transfer and dispersion throughout these lagoons. See EPA partial mix lagoon studies. These studies are excellent for increasing turbidity and treating sewage at 350-1500 watts (0.5-2.0 hp/106 gals.) per million gallons. DO NOT apply these high levels of horsepower to shallow recreational or aquaculture ponds.
Recreational pond industry specifications to improve water quality equates to 0.01 to 0.25 hp/106 gals. using grid powered diffused aeration to provide very high levels of oxygen transfer and dispersion throughout ponds.
Langston University Fish Pond studies show 0.8 cfm of air @ 15 psi., with a DIY system cost of $675-1620, and powerbills of $377-671/yr. for 1 acre fish ponds 3-10ft deep.
Application of these 1 cfm/acre standards using PEC Solar Aeration equipment with add-on airlift tubes and PEC-45/90 diaphragm air pumps is as follows:
Unit Model hrs/day * pond depth #units/acre fish lbs/unit model max
EKBS-10 24 3- 6 ft 4 -8 50
EKBS-15 24 3-6 ft 2-4 100
**G2V-STAR 24 3-20 ft 1-2 1000
***Eco-Aerator 24 3-20 ft 1-2 1000
*There is no max depth when using an airlift aerator draft tube with any PEC solar aerator. Simply increase the length of the draft tube to the desired aeration depth. OTE is based on coarse bubble diffuser @1% foot and depth is calculated at 3-5 feet.
** Unit to be mounted on flat well drained area above shoreline. Also known as the EKBSR-1, shore mounted aerator.
*** Unit includes floatable mount for wet or dry shoreline.