Remember; all just my opinion and views.
I'm also not the best at trying to explain things
I'll just jump in on what
@Dr Mike Oxgreen has said quickly; although this STC-1000 type (and ATC-1550) powers 1x heater (or more providing it's within limits of the controller and wired as such) it will only control 1 channel on/off so either all heating on or all heating off. If the only worry is a heater 'overheating' then providing the 1x heater is powerful enough and this is the only concern then why bother with 2x heaters if you have the power with 1?
*Heater failure is a different thing so then maybe add 2, whether that's using the one channel type or one that has 2 separately controllable ones would be your choice.
All of that said, it looks like things have moved on
Exactly, I've been the bare bones route before but for £20 you have the box with 2 sockets already in place
Ok, 1 is heating and the other cooling as standard but I know they could be easily adapted given the knowledge and ensuring things were done in a safe manner, meeting regulations and specifications. You couldn't buy the bare bones parts for that, I'm sure.
The pump flow is too much for the outflow to cope with, so I've temporarily added a hook and tube to run an extra siphon down to the sump
So, onto the sump side of things we go..........the photo helps a lot as we can now see that there isn't a weir/overflow but just a drilled inlet/outlet so the photo helps a lot.
Unsure how big your sump is but your display is somewhere around about 180 Litres.
A quick side note; I might suggest looking to get something over the end of the extra siphon as a temporary measure even if it's a course piece of sponge and rinse it daily, just to stop fish etc getting sucked in so easily, read on for possible resolutions to the pump/flow issues.
I can see ways around this but are mainly influenced by how you'd like to proceed, have a think and ask any questions you might have. Remember I'm
Do you really want a sump or would you be happy with an external filter or 2? - No wrong answer.
Some options below overlap either directly or in a fashion as to staying with a sump or changing to external canister type filter(s).
-Easy way to resolve the issue with pump power is to look at a smaller and/or one with an adjustable flow rate - I think the Jecod DCP-2500 might be worth considering as an excellent, value for money pump with electronically adjustable flow, range from 750-2500 LPH although I'm unsure what you have at the moment so also assumes this alone would resolve things.
@Geoffrey Rea will likely support this product also.
-lookup Geoff's build where he uses an external weir/overflow box to possibly give your sump more flow in and 2 returns which is easily enough done.
-Depending on bulkhead fitting/ hole size drilled in glass etc you maybe able to just add a simple 90 degree with a drilled piece of pipe like a more conventional filter inlet, you could probably plumb both an inlet and outlet into the holes, again probably depends on sizes drilled in aquarium to a degree. (sump/no sump)
-If you wanted to run 2 filters or use both intakes for the sump then you could use both holes for inlets (hole size drilled) and you could assemble a long spraybar which looped over the top and spread the width of the tank in between the intakes.
I'll assume you're now very confused?
- Just ask if you want any more input or better explanations.