6500k is fine. A simple Par38 screw in bulb will work.
Sand and mud do the same thing in terms of creating anaerobic areas that consume nitrates. With mud you can get that in 2 inches depth., With sand you’d need upwards of 4”, preferably 6. . Mud also adds trace elements slowly. Personally mix sand and mud together and make it 3-4 inches.
Ceramic bio blocks, balls, whatever are highly porous which is good, but IME they fall apart and start to crumble into mush when handled. At least that was my experience with Marinepure. Rock rubble or seachem matrix is a better choice.
You can add snails but you’d want to keep them out of pumps.
Couple of ….
IME was growing grape caulerpa like crazy with par38 bulbs for a few of years. Decided to upgrade my lights. Bought an
Amazon version similar to the Menards light op posted above. To my amazement within a few months started to see cheato starting to dominate and didn’t even know where the cheato came from since I didn’t knowingly put any cheato in, nor ever saw it before i changed the lights.
Another thing is flow. Found slower flow in fuge gave debris a place settle. That kept my water clearer, then gave up socks and rinsing them every 3-4 days. Don’t miss that. That was over 10 years ago. On a newish tank socks is a good idea.
If your fuge is inbetween the skimmer and the return pump chamber you can increase or decrease flow in the middle/fuge chamber by using you uv/phosphate pumps. Put the uv pump in the return chamber dumping into the first/skimmer and you increase the flow. Put the uv pump in the skimmer section, bypassing the fuge and dumping directly into return chamber lows the flow. On that front will add you should consider combining your phosgard and uv onto one single pump to avoid unneeded pump heat.
It’s a good idea to have a coarse sponge or screen between the fuge section and the return section. That will need regular cleaning.
Running your fuge light schedule opposite your display tank lights will help with ph swings at night when lights go out. This is true for refugium or algae scrubber lights.
An algae scrubber will remove more nitrates and aerate the water much better than a fuge. ATS will also need to be cleaned/ harvested more frequently. Personally like a fuge for it’s added diversity and it’s not like you cannot add an ATS also, if you have a fuge and want to, or need to, lower nitrates further without water changes.
