I traded up to a 1200 GPH
MAG submersible. Having hooked it up, I can say this is the far better solution..
had sold me the 700GPH model as the "jetstream" system handles 600GPH.. However, they failed to take into consideration (as did I) that this 125g setup contains 2 full jetstream systems - two inputs and two outputs..
Could I have gone bigger? Perhaps, but this seems to be cranking water right along and I know it won't cause an overflow.
The Pondmaster 1200 can move 1150GPH at a head of 3', which is what I'm dealing with. Hooked up, both sides are getting the same movement as I was trying for earlier, and the outputs are actually generating significant current, rather than just trickling out as before.
Thanks for the suggestions! This is an excellent forum..