I went with gate valves and lots of unions .... I used the colored PVC from bulk reef supply just for style :-) The biggest issue I had was connecting to the return on the RedSea. I ended up having to use the barb it came with. I wanted to do a direct connect and not have a barb to slow flow. Its a weird metric connection I never got to work.
Also I recommend changing the return outlet into your tank to this adapter. RedSea uses metric stuff here again.
https://vividcreativeaquatics.com/sh...34in-loc-line/
then a Y line lock - i just use 1-2 line loc pieces after that. They also have a nice random flow thing ( i dont use ) You have to be careful not to push this too deep into tank as it can cause a syphon into sump when return pump stops.
for a ATO tank I had to have something that was wife approved so I spent a little extra and got a
https://advancedacrylics.com/collect...off-new-design
I think its 13gal I cant remember. Lasts about a week. Very happy looks and works great. Be careful to not let the ato pump line get into the sump and create a back syphon. I use a little 1/2 pvc then stick the ato pump line into that to break syphon.