I use a two pump system, and this one being controlled is a 12vdc pump used for HLT circulation and sparge only. Instead of switching the ssr with 5v I bumped it up to 12v 750mA and it is enough to power the pump.
None of that makes sense. If you try to control a DC load with an SSR it will never commutate and keep conducting even if you remove the gate signal. The gate signal should have no effect on the output (other than switching it on an off) as all it does is light a LED. The led shines on photosensitive device connected to the triac or SCR's thus isolating the control circuit from the AC circuit.
The only thing I can thing of here is that somehow the gate signal is getting to the motor and that doesn't make a lot of sense either.