What would you put in a 70 gallon tank?

[woodward]

I have a overflow sump tank with 70 gallon water capacity and around 56 gallon swimming capacity. right now i'm trying to get ride of algea and bad luck. fish have been dying for weird reasons since i bought the tank so i'm fed up and i'm going to take my fish out, turn the lights off and KILL the bad algea and hopefully whatever is causing my fish to get sick. afterwards, i would like to do an agressive tank. the tank is 18" by 18" by 36". I'll have the sump still in action and a good bed of aragonite substrate in the tank. I don't have much large live rock but lots of fist size pieces. I would like to have a lionfish but i could be pursuaded otherwise. I realise the tank isn't huge so maybe one fish would be all i could put in it. I would like some sugestions on what type of fish and what type of environment agressive fish like lionfish prefer (what kind of "home" do i give them) thanx very much!!

 

[barkdog]

Sounds like you have some water chemistry problems that are killing your fish. What fish did you have in there? What kind of filter set up do you have? Also 18x18x36 doesnt equal 70 gallons. Thats about 50 gallons total capacity.

 

[woodward]

i had a blue tang, a chromis, a royal gramma, a large clarkii clownfish, a mandrin, a blue starfish, 2 percula clownfish, and i think thats all. corals also didn't survive well and i've moved all of them to another tank where they are either recovering of thriving. i've now emptied the tank of all fish and pretty much all live rock. i'm planning on trying to fix the water quality in order to get a fresh start. all i've got for a plan so far is cleaning the substrate, turning the lights off and possibly adding a HOB filter with micro fabric that would clean the water. anything else i could do??? and you're right, i was rough with the mesurements but i think the true swimming capacity is 56 gallons, but it contains about 70 gallons of water because of the sump system i have. I looked into some options and my rough plan is to (once the tank is healthy again) create a habitat for 1 or 2 dwarf lionfish and invest in halogen lighting to start a coral farm. i realise there might be some conflicting requirments between fish and coral but it's only a rough plan. anything i should be aware of??

 

[barkdog]

If you're going to eradicate everything in the tank, why bother turning the lights out and waiting weeks. If you did that, then you would have a ton of die off in the water, and would have to cycle that out of the tank. Just start over. Empty the tank and sump. Wash or replace the substrate. Cycle the tank again.
I think you probably had too many fish in the tank. I'm not sure if 2 dwarf lions need more room or not, but I'm sure someone else here can weigh in on that. If you do get aggressive meat eating fish like that, be sure that you have a good protein skimmer, especially if you are planning on making it a reef tank.
I don't think dwarf lions would be the best choice of fish to have in a reef tank. Maybe a butterfly or a dwarf angel would do well. Clownfish are always cool too.