Aerator pumps flow in reverse

I've been lurking WW for a while, time for me to chime in.

Aerator pumps (Tsunami 1200, Rule 2000, etc.)have very little restriction in both directions if they are not on. If the output of one pump is hooked to the output of another pump, couldn't you fill and drain ballast bags through the same hose? The fill pump would have the input attached to a through hull fitting below the waterline, and the drain pump would have the input attached to the ballast bag, the outputs would be connected with a hose. Providing only one pump is on at a time, it should work and I don't believe any damage is done to the pump flowing in reverse if it is not on. I've been working on a semi auto ballast system for my boat(using WW as a reference), and have not seen this done. I think it will work.

It should work, but I bet the pump that's not running will be a pretty noticeable restriction. People on here have tried it in the past, they may chime in. It might help if you ran the fill pump in reverse while draining & vice versa.

If you added check valves to keep the water from flowing out of the fat sac, this would not work as the flow would only be one way.

It works good running through two pumps and the restriction is not a big deal.

I've had problems with the fill line siphoning back. So, I've had to add check valves. Good luck with preventing that.

I've used two aerator pumps mounted together to create a reversible type pump before. They were two of the tsunami 1200 pumps and mounted in the bilge below the water line to the raw water line for the engine. I never needed any check valves but did put ball valves going to seperate ballast bags. The system worked great and I was able to fill or empty multiple bags at once. You will never have to worry about burning the pumbs out to. I left one running all night and never had a problem with it after that. Some of the other benefits to a system such as this is the low amp draw and these pumps move water very quickly. I was also able to fill and empty while under way.

Question, If you went through the process of buying a second pump why not just run the second out another fitting? Granted you do not have to drill another hole in the boat but chances of it working properly are better.

Thanks for all the input.

tuneman, I am going to be using a RV waste gate valve to eliminate siphoning, so no check valves.

kikitlo, actually, there will be six pumps total and three bags. It is a direct drive boat, and I wanted all the pumps to be hidden, I also didn't like the idea of drilling holes in my boat. That being said, I am also going to T off of the raw water intake.

I'm working on posting pictures of the install, but I dropped my digital camera (about 50')and now I need a new one.