Hi, I’m hoping someone can help me out - I’m struggling with a few things on our aquarium at the moment, water flow and high nitrates. We had this tank custom made but when it turned up they had changed the design of the sump from our original designs and installed all the piping in a way I wouldn’t have thought was best practice! I’ve had one issue solved on this forum with the weir so hopefully I can get some help on the this The tank size is 1568mm (L) x 685mm (H) x 456mm (W) and sump is 760mm (L) x 457mm (H) x 370mm (W) Our nitrates are currently coming out at 40 on an API test kit and 50 on a Red Sea test kit. No matter what we do they don’t change. It’s a 640litre tank and we’ve been doing 140litre changes a week for the last 3 weeks but they haven’t moved. We are making our own RO water which has tested fine. Stock we only have 3 pearl scale butterflies, 2 Bangais, 7 chromis and a few hermits. There is also a sand sifter star fish and sand dollar in there with a couple of snails. I’m noticing the weir doesn’t really suck the water through the slots - we have slots at the top of the weir and bottom, stuff does go through them just casually - if something floats past it, it won’t get sucked in. Our return pump is currently running at around 6000lph. I’ve noticed the outlets they installed aren’t pushing the water around much - they have put 3 locline outlets on a PVC pipe shown in this pic: Because the water flow was doing much I’ve added a powerhead to the top right corner blowing towards the weir in the back left of the tank. In the sump the first compartment has a filter sock and some live rock, the second has the skimmer and live rock, the third has some sachem matrix and final is the return pump. We also have a light algae reactor on the side with Cheato algae in it which I’m replacing with some pellets to help with the nitrate and we have a UV filter. My questions are - how would I get the best water flow in the tank to make sure things are sucked up into the sump and don’t settle and is this sump the best layout, should I consider doing something else to get better filtration. I have a feeling the sump isn’t really big enough for the size of the tank but it’s all we could fit Our main challenge is keeping the tank looking clean with no equipment on show: Thanks for any help - sorry for the long post too!