Setting up half saltwater half discus tank help

Sounds like a cool project! My only concern would be the temperature difference between a reef tank and a discus tank. Reef temp would be too cool for discus and discus temp would be too hot for reef.

you could always divide the tank with an air divider this would require to silicone another piece of glass next to the one in the tank. It would provide a heat gap if your tanks are going to be different in temperatures.

There is no need for 4xt5HO on a planted tank. Especially a 3 foot tank. It would have to be 3 foot deep to justify that. And even then...

My main concern would be salt creep gettig into the discus side. Would be an interesting tank if you can make it work though.

Just my thoughts, but i do not believe the two different water temps would be an issue because it takes water such a long time to differ in temp.... this said if your running two seperate heaters then you should be fine. dont hold me to it though. I do agree with Sharkfood however. i believe the salt creep frome evaporation could be an issue. Perhaps a horizontal piece of glass roughly 8" wide ontop of the divider could fix this? or minimize it? Feel free to criticize my thoughts. I am also learning.

As long as you do weekly water changes I think it would be fine.

I think temperature may be something to look into as well as the relative water volumes of each tank. You may be surprised how much energy will transfer through a pane of glass with the water at a high flow. I'm not positive but I would think you may need to look into having a chiller for the reef and still a heater for the FW so it might be expensive that way, but also extremely interesting.

Go for it!
-Andrew

Discus in a 3' tank?

You can avoid salt creep by having the water level lower in the reef side than normal, but it might look bad if you can see the water line. But if you used some sort of wavemaker, it wouldn't matter. It would look cool.

If you kept only soft corals, you wouldn't need extremely high flow, either. 20-25x turnover per hour.

Ohh, sort of do a matching scape too. Use plants for the discus side, and salty stuffs for the reef side that blend together.

On the reef side, you could do plants. And you could keep it even lower flow if you did a seahorse tank!