The secondary drain shouldn't have more than a trickle. How tall is your primary drainpipe? Mine is a good 5 inches lower than the secondary... Are the drains are 2 different sizes (meaning pipe diameter)?Well sand wasn't rinsed so I need to figure out how to clean that while its in my tank and the heater is shot so I need to find a Cobalt 150w heater and I need to get a piece of 1 1/2 in pipe for the secondary drain. I have pump set to 35 percent and the main drain all the way open.
How many gph is your pump rated for? It may simply be too powerful.
I have a NIB Eheim Jager 150watt heater I can sell you - got it on sale a few weeks ago.
Regarding the sand, if it's what you got from me then you already knew it was rinsed but had been sitting in a bucket for months... That being said, the remaining gunk should help feed the bottled bacteria you add and help cycle the tank. Filter sock in your sump should take care of any manual cleaning. (If you're talking about other sand, ignore the above comment.)