Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
There are a couple of possibilities.
Both use 2 tanks, and 2 'machines' (macros in one, micros in the other)
The cheaper is to use a timer and a small pump in a bucket. Make sure the timer can be set for every other day. You will have to practice to see how long to run the timer (to run the pump). Do several checks as the bucket empties- it might be enough of a change in head height that the pump will not deliver as much when the bucket is getting low.
The more expensive option is also more accurate. It involves a pump very similar to the intravenous system used in hospitals. This is very carefully metered out.
In either of these set ups run the tubing to the tanks, and include a ball valve on the lowest tank. Then shut it down to force more fertilizer up to the higher tank.
If the tanks are on the same level, then the smaller tank gets the ball valve so the larger tank gets more fertilizer. Again, this is something you will set up and practice with to get it right.