Hi All,

I've decided after having a reef tank for about 5 years now to have a go at a planted tank too. I have a Red Sea Reefer 250 that I am going to turn into my planted tank. I am UK based if that makes a difference in recommendations.

Have several questions:

1. I have an RO/DI unit for making clean water I will need to keep this for my marine tank and top off water but I heard somewhere that I could use it to make freshwater (i.e. use it to remove Chlorine/amines). Is it true that in order to do this I basically disconnect the DI resin and just run the output of the prefilters and RO membrane to make straight to tank water? Or is it the case that if I do this then I need to add freshwater salts back to the water similar to making saltwater?
2. I am looking at black/dark brown substrate for the new setup (the price of which makes me wince - I thought keeping a reef was expensive...), anyone got any recommendations for best for price. I estimate I am going to need in the region of 30-40 litres in total.
3. Ages ago when I helped set up a tank at work, there was undersoil substrate like interlocking X shapes (like you might see at on a sea defence), that you can use to help keep the substrate in place on slopes. Does anyone know what this is? Is it still even sold?
4. Coming from a reef tank I might just be being paranoid about flow. Currently I plan to remove all the powerheads and just leave the return pump attached to the tank. It is set to do roughly 7x flow, is this enough or should I be upping the flow or leaving some powerheads? Should I be lowering the flow?
5. Any recommendation on plants? Currently on my list are anubias, java, and subwassertang. Always wanted a mangrove too.

Thanks for the input!