I'm going to be a little critical here. Don't take it personal it's truly meant to be helpful
You can see where my over flows come together at the T above the bio balls.
I would loose the T on the drain lines and plumb them seperately. There's no good reason to tie them together like that. I would also loose the bioballs as they are not needed. See if the A-hole that sold them too you will give you credit for them.
I need to get that ball valve i have on on the lil Herc pump but I never thought about one on the return till I cut the power and the sump continued to fill up then I had that O S___! factor.
The ball valve is not going to help with the back flow. It just allow you to control how much flow is going thru the tank when the pump is on. If the pump is a little overpowered for the drain system or the drains are running near capacity and loud then many times the ball valve between the return pump and the DT could be partially closed to restrict flow. For what it's worth I don't like the way the return pump is plumbed over the top of the sump. It's has the potential to loose it's prime, run dry which could lead to overheating a detroyed pump and possibly a house fire. I'm not familiar with that pump. What is your GPH going thru the sump after headloss and how did you come to the conclusion to use that pump?
So that my thing now is the overflow how can I add something to what I have now to prevent this Im on craigs now lookig for a 20 to 55 gal tank to used just as an overflow.Some thing that will fit in my storage area on the side were the Bio balls are at now.
It's possible to use a second tank as an overflow tank, it's basically having two seperate sumps. But the bigger question is how are you planning to plumb them together and why do you need an overflow tank in the first place? I would either make the one you have work or get a bigger sump and possibly a Refugium. It's likely that you can make some adjustments to make the current one work. I do not recall seeing the size of the current sump. I followed the link but it didn't jump out at me there either.
Keep in mind this is just my opinion and you will have to make your own informed choices. If it were me I would loose the current sump. I would rip out the baffles and scrape the excess silicone and use it for a QT. I would find the biggest tank that I could fit into the my space for the sump and I would redesign it from scratch. A few well placed baffles and you would be much better off then you are now. The center section of the current sump appears to be designed for a refugium. The water level looks like it's much higher then the sump is designed for. That's not necessarily a problem just an observation. If you were running the sump at its designed water level then you might have enough room for the backflow. The depth of the return lines in the DT will effect the amount of backflow you're getting. Although I'm not a fan, many people use strategically placed holes in the return lines to limit the amount of backflow. My point is you have other options and I think you should slow down and reconsider all your options carefully before proceeding.
