Pond aerator powered by solar is on the docket - Page 1
Forum section: electronics / projects

author: Ra
author_rank: Newbie
timestamp: August 03, 2020, 07:07:17 pm
content: G'day,So i have got 3 x 250W modules - need to aerate 2 ~50' diameter x ~8' deep ponds.Looking around for a DC air compressor - any recommendations out there? I would certainly like to avoid an inverter - the more I look around the closer I am to considering that option. Batteries are not to be utilized - just running the pump when the sun is out.I'm in Ontario fyi.

author: JimRemington
author_rank: Regular Contributor
timestamp: August 08, 2020, 03:22:37 am
content: There are a variety of submersible water pumps intended for use with solar panels (direct connection).To aerate ponds, it works quite well to spray water into the air.

author: calzap
author_rank: Frequent Contributor
timestamp: August 08, 2020, 04:37:55 am
content: Anyone interested in pond management should subscribe to Pond Boss magazine. They've had recent articles on using solar for powering pond aerators. BTW, spraying water into the air from the surface looks nice, but doesn't do the main job that the usual type of pond aeration should do ... namely stir the pond ... especially bring water from the bottom to the top. The reason is thermal stratification. In warm weather, the sun and warm air at the surface make the water less dense there. At the darker, cooler depths, the water will be denser. This difference leads to stratification, and the bottom soon becomes anaerobic. Only microbes will live there. Putting an aerator at the bottom lifts the bottom water to the top, which means top water goes to the bottom ... stirs the pond. This prevents stratification and the deadly anaerobic condition at the bottom.There are aerators that directly oxygenate the bottom of the pond by diffusing oxygen into the water. They are very expensive.Mike in California

author: JimRemington
author_rank: Regular Contributor
timestamp: August 08, 2020, 02:46:49 pm
content: So, a pump that moves water from the bottom of a pond to the top doesn't "stir the pond"?

author: calzap
author_rank: Frequent Contributor
timestamp: August 08, 2020, 06:20:45 pm
content: Quote from: JimRemington on August 08, 2020, 02:46:49 pmYes it does. But a lot of (probably most) aerators that spray water into the air have their intakes within three feet (1 m) of the surface. Look at some of some of the fountain-type aerators made by Kasco Marine, Easy Pro, Otterbine, or Aqua Master. These are impressive to watch, but they only aerate water that already has a high oxygen level. One of the problems of extending the intake of a centrifugal pump, piston pump, or air-lift pump to the bottom or near it is clogging ... lots of muck and debris down there ... which is why it's not usually done. OTOH, an air-stone or diffuser doesn't have this problem, which is why they are by far the preferred method of stirring a pond.Above, I'm writing about real ponds, not little garden ponds that are basically large, sunken, outdoor aquariums.Mike in California

author: JimRemington
author_rank: Regular Contributor
timestamp: August 08, 2020, 08:49:26 pm
content: It never occurred to me to consider commercial decorative fountains, but I understand the shortcomings.It seemed obvious that if one wanted to use a solar powered water pump to aerate (as does a friend with several large ponds bearing fish), one would draw from the deepest point.

author: calzap
author_rank: Frequent Contributor
timestamp: August 08, 2020, 09:30:19 pm
content: To find out more about aeration, I suggest visiting forums.pondboss.com. They have a forum section dedicated exclusively to aeration.Mike in California

author: Seekonk
author_rank: Super Contributor
timestamp: August 09, 2020, 01:20:09 pm
content: Wish I had a pond because this is something I'd love to design. I'm a proponent of batteryless PV systems. I have a LG clothes washer that runs off panel voltage with no battery. Most old MSW inverter H bridges will work off any voltage you feed them. Just power the control circuit with about 50ma @12V to control system. Boost up the AC voltage with an auto transformer. Small pilot panel to turn on inverter when sun intensity is high enough.

author: DaJMasta
author_rank: Super Contributor
timestamp: August 09, 2020, 06:00:08 pm
content: Why not standard bubblers? You can get them in large sizes, and take relatively low volume, low pressure air input - I've got a much smaller pond but a 20W panel and a cheap DC air pump get a surprising amount of circulation (the rising air bubbles actually move a lot of water). Maybe a collection of smaller, inexpensive pumps/air stones would give you some redundancy for failures but still get the flow rate you need.Another option could be bilge pumps. You can commonly get 12V or 24V pumps with a high flow rate that are fully submersible and inexpensive, then you just need to keep the gunk out. In the same case as a bubbler without getting very small bubbles, gas exchange is more about churning the water to have more time near the surface than the actual value of the extra surface area of the bubbles. Just moving the water from the bottom to the top means the least oxygenated water gets put on the surface, which increases the rate of gas exchange and raises the average oxygenation level.While I think circulation and/or bubblers will do the trick, especially if it's highly stocked, it's probably good to see what professionals do. I believe most of what I've seen in fish hatcheries in those circular tanks is high flow pumps with air mixed in - something like a powerful DC pump on the shore that sucks up water from the bottom of the pond and introduces a bit of air with a venturi and then dumps it back into the pond. Maybe not pretty/soothing, but effective.

author: calzap
author_rank: Frequent Contributor
timestamp: August 09, 2020, 08:33:58 pm
content: Solar-powered aerators are readily available as packaged deals ... lots of them ... just use google. The circular (or rectangular) tanks used at hatcheries have special needs. The stocking rate (numbers of fish or kilos of fish per m^3) in them is usually much higher than what is found in ponds and lakes. They need a high water flow not only to provide oxygen but to remove carbon dioxide, excretory waste and uneaten food particles. In some cases, it's needed to control temperature or disease organisms.The problem with using a water pump with an intake near the bottom is sucking-in gunk. Unless the pond has a gravel or rock bottom, clogging will be perpetual problem. Even with a gravel or rock bottom, there will still be drifting or swimming objects ... leaves, twigs, fish, turtles, etc.. A grill or grate can help, but even these can become plugged. Many water pumps don't take kindly to a clogged intake. Without safety detectors, a clogged intake can destroy them.That's why air stones or diffusers are the preferred way of aerating most ponds ... clogging with muck is not a problem. "Diffusers" is a bit of a misnomer ... they are rubber diaphragms with many small holes that release bubbles.I've used air stones in my pond for 15 years and have been happy with them. I use Thomas air pumps that run 24/7. Only maintenance on them has been replacing the diaphragms and air filters periodically.One problem folks encounter when installing aerators is that most rubber of plastic tubing (or pipe) floats when it's full of air. Heavy wall plastic tubing that stays down is available but expensive. I use standard wall tubing but have periodic weights in the form of short sections of metal pipe around the plastic tubing.Again I urge anyone with a serious interest in aeration or anything else to do with ponds to visit forums.pondboss.com. There are folks on that forum who have been managing ponds for decades who are happy to give advice.Mike in California