very short intervals

[justinl]

I apologize for the noob question, but are there controllers capable of having 5 second long intervals? I need a controller/timer that will turn on a fan for 5 seconds, then keep it off for several minutes, repeat.

I would assume yes since I know people use them to control maxijets on waveboxes if im not mistaken. Can you point me to one that will do this?

[Myka]

My RedSea Wavemaker does something like that, but you can't really controll when it comes on or off, it just its own pattern. Why do you want the fan to come on and off all the time? IceCap fans sense temperature and will come on when needed, and go off when the temp drops.

[justinl]

sorry, I probably should have explained. Im currently raising copper rockfish (Sebastes caurinus) larvae at work and there's currently a big problem with having the initial birth of larvae settle on the bottom of the tank and suffocating there. The idea is to have a slow rpm fan (underwater) come on for a few seconds to blow the drifts back up into the water column, then turn off for a few minutes so as not to damage the very very delicate larvae. It only takes about five minutes for the drfts to start accumulating.

We also have oxygen bubbling in the tank but vigorous bubbling will kill larvae so that's not an option.

edit: also, because it is not for a powerhead, but for a fan instead, i need the controller to accept a standard three prong plug.

[Myka]

The RedSea Wavemaker just may do the trick for you. It has different settings for gentler or more aggressive. If you were closer I would offer for you to try mine out for awhile before you decide to buy one because they aren't cheap. Why don't you use a small powerhead instead of a fan? I imagine the fan will rust in no time. MaxiJet puts out a MiniJet and MicroJet powerheads, which are tiny and have adjustable flow. The smallest MicroJet goes down to 32 gph and is something like 1.5 x 1.5 x 2". They are cheap too, about $20-25. I know J&L carried them awhile back.

[justinl]

powerheads are a no go in a larval tank because they'll chop up the larvae. the fan im talking about isn't what you're thinking about... it's a modified variable speed ceiling fan with a gearbox that makes it run slow... about 1rpm. the fan diameter is about a foot and a half across and the tank is 5 feet in diameter. the fan motor is on the ceiling and a shaft and fan propeller reaches down into the water. Your input is much appreciated though.

anybody know if the red sea will do the job for me?

[Myka]

Sounds like an interesting setup.