Converting tropical to goldfish tank

[stoneydee]

I have a 37 gallon tropical tank with Eclipse 3 filtration that I want to convert to a fancy goldfish tank (after finding suitable homes for the tropical fish, of course). I've got a couple of questions about the substrate and filtration. I already have one goldfish tank, so I'm familiar with what has worked (and hasn't) in the past.

First, I currently have combination sand and small gravel substrate. I really prefer larger (3/4" to 1") diameter gravel for the goldies, so I don't have to worry about anyone getting gravel caught in his mouth. The tropical tank has cycled, and I'm not going to touch the bio-wheel, but I wonder if laying a single layer of larger gravel over the existing substrate would be okay (or will I just cover up a lot of my nitrifying bacteria) or should I remove a portion of the existing substrate and replace it with the larger gravel?

Second, in my existing goldfish tank, I've got an internal canister filter in addition to the Eclipse 3 system with the bio-wheel. I have a spare canister filter (new in the box, same size). Should I take the filter out of the old tank to put in the new one, or just use the new canister filter in the "new" goldfish tank? (One of the lessons I learned with the first goldfish tank is that it is true, you cannot over filter a goldfish tank.)

Third, the existing goldfish tank is not heated, and remains at a pretty constant 72-74 degrees F, as my house is heated and cooled. Is there any significant benefit to heating the "new" tank, or should I just keep this heater for back-up for other tanks?

 

[Bluefrog]

I'm not sure, but I have a feeling that putting the larger stones on top of the smaller gravel may just create an ideal place for all the goldie gunk to get trapped under there. I just upgraded my goldie tank and only put some large (about 1" diameter and larger) pond stones in there, which doesn't even cover the tank floor. I've found this is so much better at allowing my filter to suck up the crud instead of it getting trapped as it did in the other tank. If I were you, I would go the slow route, and replace your substrate all-together. This will probably cause you to mini-cycle, but in my opinion, you will do that anyway by adding messy goldfish to a bio-system that was used to tropicals. One thing that you can do: put some of your smaller gravel into a pantyhose/stocking leg (tie off the end of course) and lay that on top of your replacement stones. Leave it for a few weeks to seed the new, larger gravel/stones. Also- besides the possibility of small gravel getting stuck in mouths, I have read that sand can harm their gills. I think of goldfish like I think of a 10 month old baby- they put EVERYTHING in their mouths!!

Yes, overfiltrate the goldfish tanks. I have an Aquaclear 300 plus a Bio-Wheel 110 on my 29 which seems to be working well so far.

I would not worry about the heater at all. I have read a lot of conflicting information about heating goldfish tanks, but it is really not necessary if you keep a normal room temperature. The only thing that has made sense to me regarding heat is if you have a sick fish and you use a heater in QT to help boost its immune system. What is more important than using a heater is that you keep the temperature from fluctuating wildly. 72-74 sounds like the perfect temperature for goldies.

Hope that has set your mind at ease some!

 

[jsoong]

If you are worry about goldies getting to the smaller gravel/sand, covering it up prob will not do. Mine like to root around & constantly move the gravel around, exposing what is underneath.

If you have a biowheel, I wouldn't worry about the bacteria too much - there is prob enough in the wheel to start, plus they will prob spread up through the substrate if there is some water circulation. If you are worry about a mini-cycle, pull the filter from the old tank to use in the new one, & put the new filter in the old tank. That way, each tank will have a mature filter, should handle anything!

Ideal temp for goldies is a bit controversial. Fancies certainly like to be kept in the 70's, but I have read that some people (Chinese breeder) says it is better kept in the 80's. I've never tried the high temp bit, so I don't know if it is true.

 

[stoneydee]

Thanks for the input. This gives me a clearer idea of how to proceed with the conversion.

I've read on the temperature thing that the fish may be more active and grow faster at higher (80s) temps, but that on the downside, it revs up the metabolism and the life expectancy is not as long. In addition, supplemental aeration is even more important, as higher temps deplete the useable oxygen. I know I want to keep the temp constant and in the 70s - I just wondered if higher 70s were better for the fish.

 

[PK Tester]

Hey...from my experience. Just cover your gravel can cause a mini-cycle even with a bio wheel. I added newer gravel to my aquarium on top of my old...it caused a mini- cycle. I change 30% of the water and with help from the bio-wheel it was done in 3 days. Some sick fish though :-( . Just some helpfull advice