Established Coldwater Tank...

[littlelegs]

I have a 30x12x15 tank.

Currently has one goldfish left in it (4 inches in length), which I have found a home for.

I would like to convert it to a tropical tank. Do I need to completely clean this tank out? Or can I leave exisiting water etc in.

I am still yet to buy a heater, what size will I need?

I have read your posts about fishless cycling. Can you cycle your tank with fish in it?


Any help much appreciated, TIA.

 

[Callum]

you can cycle a tank with fish in but its cruel to the fish so fishless is considered more humane. You will need to buy a heater but i do not know what size your tank is, are your measurements cm or inches? you might not need to drain all the water and give it a good clean but personally i would.

 

[littlelegs]

the measurements are in inches.

 

[Callum]

so thats 75cm x 30cm x 38cm so thats about 20 gallons so a 100w heater i think

 

[littlelegs]

thank you.

Will I have to do a complete water change?
How many fish and what type should I buy and when?

 

[littlelegs]

Does anyone know for definate, if i need to completely empty my tank and start again? Or if I can use the water that is already in my tank?

 

[black angel]

Ive changed from goldies to tropicals in the past and if the goldie was nice and healthy then you dont need to do anything more than a 50% water change and clean the filter out in old tank water. Add the heater and when at the right temperature add the fish, If the fish arent going in for a few days then add some flake near the filter intake to keep the filter bacteria happy and stop it from needing cycled again.
What fish were you thinking of?

 

[littlelegs]

I havent a clue to be honest, what are the most hardy for beginners?

 

[DarkEntity]

I would say that you definately should compltely GUT the tank, filter the lot. I wouldnt ever put tropicals in a tank that had goldfish in it without having it completey sanitised first. Thats just me though, some will just change water and then leave it a week or so.

 

[littlelegs]

bump

 

[Callum]

i always reccommend the harlequin rasbora its a lovely little fish and in my opinion very underated, it grows to 5cm you can get different colour strains, there hardy and can tolerate a lot of water conditions and there relitvley cheap and compatible with most freshwater fish. they like to shoal so a 5 or 6 minimum i had 3 at one point added another 2 and they were much happier.

Also if i was in your shoes i would clean out the filter and empty the tank purely because goldfish have a reputation to be messy and carry disease. The only downside is you will have to cycle it. fishless cycle is the best way and there is a pinned topic somewhere.

 

[littlelegs]

Thanks to everyone for your advice. I shall move the goldfish to his new home and start cleaning the tank.
Do i need to use anything special or just plain water from the tap to clean it out?

 

[Callum]

Best to use water from the tap ive heard you can use bleach but it requires a lot of scrubbing to get rid of the bleech. The best way is probably tapwater Also im not sure wether to use tap water on your filter so best to leave that until you get another members opinion

 

[littlelegs]

bump

 

[basia]

I wouldn't clean the filter - it is already cycled by the goldfish.
I have moved a filter from my goldfish tank to a tropical tank and had no problems at all.