Low Pressure Air (1 to 3 psi) to Run Hydroponic Ebb and Flow Systems

Not being into hydroponics, I'm lost.

What are you looking for?

Hi, Lyn, in ebb and flow hydroponics people usually have a tank of media, gravel or perlite or whatever and the roots of plants grow down though it, and there is a second lower tank of nutrients. Nutrients are pumped up and in and the roots get wetted until the upper plant tank fills up near the top and then the water gets released through an automatic "bell syphon" . This is just a way of doing the same thing in a different way. It may give better oxygenation of the nutrient solution. The second one is the ebb and float version. Sometimes people do "aquaponics" with fish living in the tank below the plants. So all I am doing is throwing a few ideas out there for those people to play with. The air pump/geyser switch combination may be more robust than the water pump/bell syphon combo because the air pump and the geyser switch can be totally independent of the tanks. On the other hand, the crud and muck in the tank can partially block the water pump or the bell syphon pretty easily and it would be hard to tell that anything was wrong. Brian

Brian,

Thanks for the enlightenment. Interesting topic, and I'm impressed by your presentations.

I grew up on a farm. We used dirt as our growing medium.

Me too. I plan to continue to use dirt! I saw one aquaponics project ever. A guy called David was experimenting with one in his apartment. It is a lot of work! He had growlights, and fishies, and plants over his aquariums and he was growing some sort of fly worms to feed to the fish. And today, I am going to see a large aquaponics set up at mason st farms open house. It is an urban farm on a large city lot and the aquaponics is in their greenhouse. I went to a presentation about how they were planning to do it last winter so you got to see the results after seeing the presentation! The guy had gone to aquaponics places in portland and elsewhere and did intensive learning before the presentation. My personal opinion is that hydroponics is too hard for ordinary gardeners and that aquaponics is another order of magnitude harder. But who knows? Anyways, it is nice to try to contribute to something like that. Many people live in cities and the dirt in cities is often suspect. If the geyser switch/ lungfish thingy helps people do it a little simpler, I am happy. Brian

Very interesting subject, please keep it up

I haven't done anything! So really there is nothing to keep up.

General hydroponics sell a 20 litre per minute air pump here for about a hundred bux. Probably $30 in the USA and I was told that it would eat through about 7 cents worth of electricity per day. It would be nice to see someone doing one of these near a little stream and using a little tromp in the stream to pressurize the air for it. A 4 inch diameter pipe going 4 ft deep in the water down-stream of a 1 and a half ft dam would give the same amount of air or more. If you think about 5 minutes fill cycle, that would be 100 litres and the grow media they used (pumice) only looked about 6 inches deep. So maybe 10 cm up and down and half would be pumice/roots so 200 litres of volume gets aereated by the ebb and flow. I just played with milkjugs in the kitchen and seems it could run a decent sized bed! This is totally ball park of course. It is not anything like real ebb and flow because the ebb part of the cycle can be much quicker and probably there are a bunch of other things I never even thought of. Brian

Adding a feedback mechanism in which the chemistry of the growing process and/or medium modulates the nutrient flow would be cool. Maybe something based on ph or CO2 production, with feed reservoirs and a solar panel for power would make it nearly fully automated and self-contained. The farmer would just have to fill the water & food reservoirs, change filters when needed and harvest at the right time.

Hi, Lynn, one problem is that there do not seem to be many low pressure air pumps that are run from a solar panel directly. I know that 12 volt bilge pumps are pretty immune to thermal overload when not running because they are in water and the water takes away the heat but probably air pumps would be more prone to overheating when there is power but not enough to pump anything. I look at the "geyser switch". What electronic component does it correspond to? It is different than electronics I guess because there are 2 "electricities" going through it. There is the water and the air. Maybe one corresponds to magnetism? Just thought that if someone correctly identifies the corresponding electronic component, we could figure out how to design another electronic analogue and do your feedback thing! Thanks Brian