I would like to have everyone's help in the final tank review. I have been staring at this thing for so long... I have cut everything and am ready to cement all the PVC fittings, but need to be sure I haven't overlooked anything. I would hate to find a problem when it is full of water that would have been simple to fix at this stage. Any and all improvements/comments/critiques are appreciated. (But some may not be used.) (Click images to view larger) This is the overview and overall look of the tank. The doors are magnetically attached at the four corners with the little push in/pop out things like on your glass stereo doors-that is them at the left side. I will be using plastic strapping material (2 bands-stuff that you would use for skids) around the tubs to keep them from popping the doors off to stop the bend out when filled with water. This is the overflow with the black cover removed. The pipes are all 1 1/2 inches with 2 durso standpipes and 2 returns. The funky "tusks" on both sides are what I am using for my return diffusers. They will be cut with slits on 1/2 of the pipe from top to bottom. These thin slits will be an 1/8 of an inch wide to allow circulation from the top to the bottom of the tank, while not letting any cephs through. The rocket scientists who made my tank didn't leave enough room for a 1 1/2 inch pipe to fit between the top and the overflow so this flex pipe will bend to fit between and spread the output. This is where it gets complicated. A. I modified the first version by adding a second 2" pipe feed from the wet/dry. The Wet/dry is on the right of "A" and the flow goes from right to left. The second tub (center) is for additional safety of overflow and for mixing seawater for water changes. There is a cap on the inside of tub 2 to mix salt and let sit for a couple days and open to release. I then use a python no spill to add and subtract water from the system. These tubs are 30 gallons each. So I only have a 90 gallon sump total for 240 gallons. B. This shows the ball valves that control the water that comes in from the dursos and drops to the drip tray that is over the bio ball tower. I have over 30 gallons of bio balls-20 in the air for ammonia removal and 10+ in the bottom (not there in the photo) for nitrifying (notice the higher output in (A) for the 1st tank.) C. the return that has the 2" pipe with a split and ball valve is like in the "sump" article that has been posted recently. The return to the tank is split to (2) 1 1/2 pipes and up to the bulkheads. D. shows the return from the third tank to the pump. I don't like that there is a 90 deg. and two 45 deg. in the 2" pipe, but I couldn't figure out any way around it. I have a union on the pump. It will run 35 gpm at this head, but with the angles, splits, etc. it should move down some. The "tusk" returns hopefully will displace out that much water over a wider space so I don't have a venturi going in the tank itself. The skimmer will go in the last tub with the pump return. I may have a micro bubble problem since I have no baffles. I am thinking of using a smaller tub that I could put inside the last tub and the skimmer nested in the smaller tub. Water flows through the skimmer and will overflow out of the smaller tub into the larger tub, making a baffle. Thanks everyone!!!!