Quote Originally Posted by salt36 View Post
I used 4mm acrylic(perspex) for lids and they have all warped badly, probably from having the light above them or the water temperature or both.

I siliconed acrylic dividers in the glass sump before I realised the silicone does not stick to acrylic!
They may leak over time but the silicone on the glass will keep them in place.

Mate you may want to plumb the pipes next to an edge or between two pieces of acrylic, it is awkward to remove when it comes time to clean the filter pads.

One overflow should keep up with two pumps no problem.
25mm PVC will handle around 5,000 litres per hour.
The one pane of glass will work but maybe experiment first to see where the top needs to be to keep your desired water level.
I am guessing my pump moves around 3,000 LPH and my weir is 600mm long. I have 5mm of water spilling over it.

any chance you could send me some pics? ill go take a look at your posts now but incase you've already posted