I see some things I would change in your design if it was me. There are some questions that need to be answered first before we can answer your questions.
BUT I will answer your last question. I would not use check valves in your return lines because algae and other debris can get stuck in the hinge of the gate keeping it from closing when it needs to. People have come home to flooded rooms and dead fish because their check valves failed. Even lines with multiple check valves. If you do use them it is a good idea to have other fail safes.
On to my questions!
1. Does your 400 gallon tank have built-in overflows? This will determine what size pipe to use and how many drain pipes you will need.
2. Have you considered having more than one sump on this tank? This does have an advantage as you can have twice as much media plus more water volume. Also if 1 pump fails you would still have one of the sumps operating and filtering the water until you can replace the pump. The next question kind of goes hand in hand with this question.
3. What size tank were you going to use for your wet/dry sump? Ideally you want the wet/dry sump to hold 15-20% of the display tank volume at all times. For your 400g that would mean 60-80g in the sump at all times. While still having room for the excess water that will drain into the sump during a power outage/pump failure..
4. What exactly do you want to get out of this sump? Such as what functions do you want it to perform? Do you just want it for more water volume and biological filtration?
5. Out of curiosity what are the dimensions of this tank?
I would definitely suggest getting different pumps or another iwaki 70rlt because 1500gph on a 400 gallon tank is only a 3.75x hourly turnover rate. That isn't much at all. People tend to aim for 7-10x hourly turnover rate.
You should read Fmueller's 240 gallon tank build that is here. It is a good read. He did a DIY sump which you could possibly get some ideas from. Though I wouldn't have the returns be through a USJ system.
Anyway, let us know. :thumb:
BUT I will answer your last question. I would not use check valves in your return lines because algae and other debris can get stuck in the hinge of the gate keeping it from closing when it needs to. People have come home to flooded rooms and dead fish because their check valves failed. Even lines with multiple check valves. If you do use them it is a good idea to have other fail safes.
On to my questions!
1. Does your 400 gallon tank have built-in overflows? This will determine what size pipe to use and how many drain pipes you will need.
2. Have you considered having more than one sump on this tank? This does have an advantage as you can have twice as much media plus more water volume. Also if 1 pump fails you would still have one of the sumps operating and filtering the water until you can replace the pump. The next question kind of goes hand in hand with this question.
3. What size tank were you going to use for your wet/dry sump? Ideally you want the wet/dry sump to hold 15-20% of the display tank volume at all times. For your 400g that would mean 60-80g in the sump at all times. While still having room for the excess water that will drain into the sump during a power outage/pump failure..
4. What exactly do you want to get out of this sump? Such as what functions do you want it to perform? Do you just want it for more water volume and biological filtration?
5. Out of curiosity what are the dimensions of this tank?
I would definitely suggest getting different pumps or another iwaki 70rlt because 1500gph on a 400 gallon tank is only a 3.75x hourly turnover rate. That isn't much at all. People tend to aim for 7-10x hourly turnover rate.
You should read Fmueller's 240 gallon tank build that is here. It is a good read. He did a DIY sump which you could possibly get some ideas from. Though I wouldn't have the returns be through a USJ system.
Anyway, let us know. :thumb:
How is the water going to be returned back to the tank? Do you plan on making under gravel jets? thats something I would recommend to keep from getting any dead spots in the tank and having excess food and waste accumulating in one spot and it keeps the same stuff suspended in the water longer so it can be sucked up by your filter. One thing to keep in mind is that 4300 gph is going to create a lot of water turbulence. 3500gph was a lot in my 600 till I downsized the pump.
