Many thanks. It is still working but the 18 LEDs proved way too fast growth. Not algae problems but pruning every other day is not my thing
I am now running it with just the front and back rows on and it is still growing pretty fast.
I should add just to address the concerns of MDF swelling. The acrylic paint seems to have done it's job of sealing the MDF very well. There is no swelling. The only thing I have had to do is wipe some mould off the bottom of the inside rails once. It was on the surface only so wiped straight off with no stain.
Looks at least 10mm, given that the lights are 12mm. There's also a big difference between cell cast and extruded acrylic for how well it does under heat. A lot of the thin stuff is extruded and bends like crazy.
It is acrylic. made an 8mm one for my little 30 litre and that bent so with this one I went for 12mm.............Yes it has bent. If you look where the 2 pieces meet in the centre the lift up a little and the same at the ends.
It isn't from the heat of the lights. The Luminaire one is the same thickness and has the heatsinks 2mm from it and it has hardly bent at all. The bending is from the moisture and humidity. It serves it's purpose though and keeps kids toys from going swimming.