Starting a new fish-only tank

[dacia]

I want to start a fish-only tank. It is small, only 20 gallons, and it used to be a freshwater goldfish tank. I have never had a fish-only marine tank, I have heard that they are different from reef tanks, so I have a couple of questions.
Should I add any live rock to it? If so, how much and what kind (Florida or Fiji, etc) do you suggest?
Do fish-only tanks require special lighting as do reef tanks?
Also, I have never converted a freshwater tank to a saltwater tank, but since I plan to use the same filters and water, how long would you expect the water to cycle again for my new fish?
I know these seem like dumb questions, but any help you can give me is greatly appreciated!

 

[beaslbob]

Although extremely popular, live rock and live sand, is optional. Base rock will provide interesting decorations for your tank.
I recommend you establish a good growth of macro algae as one of your first priorities. It will balance out the tank and prevent or at least control less desirable forms of algae.
For a substrate, plain old play sand for home depot or lowes is fine.
Whatever you do be sure the tank runs for at least three weeks before adding livestock. Thhis allows ICH to die off from lack of a host fish.
Good luck and welcome to this board

 

[birdy]

First welcome to the Boards,
Please research alot before you start you will save yourself alot of money and disapointment if you do, start with some good books, and searching on here.
First I would not use the same water and filter media when you switch over. You should use RO or distilled water, the water from your fresh fish tank will have stuff in it that will cause algae to grow in your salt tank. The same with your filter media, what type of filter is it? If it is a HOB or cannister filter, you can use them but you will need to replace all the media, the beneficial bacteria in a freshwater tank is different than in a saltwater tank so you do not benefit from using the old media.
I would recommend a live sand bed and live rock,(the amount of live rock for a FOWLR is around 1.5lbs per gallon) this will be your main biological filtration. Then you will want a good protien skimmer. You do not need special lighting for a fish only tank but I would buy a good 50/50bulb. Good luck and keep asking questions.
As a side note, keeping a 20gal as your first saltwater tank can be difficult, it can be done but you have little margin for error, it can be difficult to keep the tank levels where they should be.

 

[dacia]

I have a 150 Cascade HOB filter. The box said that it was made for 30-35 gallon tanks, but it was the same price as the smaller filter for 20 gallon tanks...so obviously I got larger and more efficient one. I also have a powerhead on the opposite side of the tank meant for "up to 45 gallon tanks." I have the edge of it angled towards the water surface. My LFS informed me that it might help aerate the water better that way. Besides, with it pointed up, the current won't slam poor curious fish into the wall!
I have always cycled my freshwater tanks with pure household ammonia (no fish, of course) which normally took 2-3 weeks without killing innocent little fish. Does the same method work for saltwater tanks? I haven't added anything like that yet because I wasn't sure, and my nitrite and ammonia levels are stabilized at 0.50 and 8.0 respectively. How long will it take to normalize?
If I do add 1-1.5 pounds of live rock, how much space in the aquarium will that take up? I really don't know how big a 1 pound chunk of live rock is.
As for the fish, I want to have 2 clownfish. Any suggestions as to what other fish would be compatible with them in a 20 gallon tank?

 

[birdy]

1-1.5lbs of LR per gallon is really not that much, I have over 90lbs in my 46gal. you can cycle a sw tank with ammonia but I haven't ever done it that way, I just throw some raw grocery store shrimp in my tanks. As far as fish, if you pick two of the smaller size clownfish you could probably add another small community fish. like; royal gramma, firefish. a general rule for saltwater fish is one inch of fish per 5gal of water.

 

[krunk]

yep, you could go with two clownfish, you could also add a blenny, or a gobie.

 

[birdy]

1-1.5lbs of LR per gallon is really not that much, I have over 90lbs in my 46gal. you can cycle a sw tank with ammonia but I haven't ever done it that way, I just throw some raw grocery store shrimp in my tanks. As far as fish, if you pick two of the smaller size clownfish you could probably add another small community fish. like; royal gramma, firefish. a general rule for saltwater fish is one inch of fish per 5gal of water.

 

[beaslbob]

as far as cycling your tank goes, I recommend you use a molly. Yes the same mollies from freshwater tanks. Don't even attempt to reuse your old water. The bacteria is not the same. You can cycle with ammonia or a shrimp but i do not recommend those. There is no substitute for a living fish. The bioload from urea and respiration are not present in other methods.

 

[wrassecal]

I don't advocate using any live fish for cycling purposes. I'm not sure where you are at with your equipment but I agree not to use any of the bio-filtration from the freshwater. I would use live rock and live sand or a raw shrimp to cycle with. Copper is deadly for sw so I just wanted to ask if you ever treated your freshwater fish with any copper based medication. It can leach back into your system. Just checking, just in case..... figi live rock is more porous and probably a little better for wallet as well. Florida is heavier. Both are good rock. And welcome to the board.

 

[dacia]

I never had to medicate the fish in this particular tank. After it was cycled, I only had 4 fish in there for 5 months before I moved them to the tank across the room to start a saltwater tank.
This may be another dumb question...but since my ammonia and nitrite levels are so high, will this hurt any new live rock I put in? My LFS has lots of live rock, but I don't want to shell out the money for something that I will end up killing.
Is it safe to put shells found on the beach in the tank? They haven't been treated with anything since I found them (2 weeks ago) and I think they would look pretty in the aquarium.

 

[clownfish2]

Dacia, Just starting as I am also, here is the very first thing that I did. I went and bought the book- The New Marine Aquarium by Michael Paletta. It has answered just about all of the questions that I had. The ones it did not cover I got answered from the fine people on this forum. Good luck with your first setup.