Have I Just Got Rid Of All The Bacteria And Introduced Harmful Substan

[pablothebetta]

Someone I know has a tank which really isn't looked after. It's around 70-80 liters and *was* (and still is partially) overrun with algae and general grime. I recently found out that they don't even do waterchanges - only a 100% change and complete clear out annually. Moreover, it's stocked with two goldfish - unsure of type, but slender bodied, short finned. I'm not sure if I'll be able to do anything about the stocking as of yet as I don't own the tank, but I decided to try to give it a bit of a clear up a few weeks ago.

I scraped as much algae as possible off the sides, but then I did something I regret. I had the filter sponge rinsed under the tap. I know that it should be rinsed in old aquarium water (aka during waterchanges), but I wasn't able to change any of the water as they had no conditioner that I could use. Have I just killed all the bacteria?

Secondly, the pieces of bogwood in there were pretty dirty so I had them scrubbed (and I must say, they looked far better afterwards for it), but again under tap water. Have I just introduced harmful chemicals into the aquarium water by rinsing under tap water, and similarly by rinsing the filter under it?

Many thanks, any advice is greatly appriciated

 

[onidrase]

Rinsing stuff in tap water doesn't introduce harmful chemicals. The sponge depending on how much you rinsed it may have a lot less beneficial bacteria in it, but it shouldn't be totally void of it. Rinsing off the driftwood shouldn't have done anything harmful in the slightest.

 

[pablothebetta]

Thanks for your reply, I'm glad to hear that it's probably not as bad as I thought

Not 100 % related to this thread, but what would some coldwater stocking options be for the tank? As I said, it is around 70-80 liters from measuring the dimensions of the tank and working it out that way, and not taking away volume for decor. Is it just pretty much just WCMMs, or would they do best with a heater and the low temp settings? I've heard both about them.

 

[Prime Ordeal]

The amount of bacteria killed will depend on how much chlorine and chloramine was in the supply you used to rinse it with and how you 'rinsed' it. If you squeezed it a lot and did it for a longish time then the bacteria colony will obviously have suffered greater damage. It's very likely that you wiped out a good part of the colony though. The good news is that goldfish are probably the most tolerant of freshwater species to ammonia (which is why they seem to survive so long in tiny bowls with no filter!) so they should be fine until the filter recolonises.

As for coldwater fish, the answer is none if they're going in with the current two goldfish as that's about the limit for that tank anyway. Also true coldwater fish limits you to goldfish but if you want temperate (i.e. room temperature) fish then you could have wcmm, hong kong/hillstream loach, rosy/golden/odessa barbs and leopard and zebra danios. The danios need a lot of swimming space though and the barbs must be in groups of six or more to curtail their fin-nipping habit. You could also keep variatus platy and paradise fish, so there's lots of colourful species to choose from. There's also bronze/peppered/albino corys for the bottom of the tank.

In the shop many of these will be kept in water at 25C or higher so when you introduce them to your tank you either have to make your tank about that temperature and gradually, over a couple of days, lower it to room temperature or very slowly drip acclimatise them.

 

[pablothebetta]

I was wondering about stocking if I was able to get the goldfish rehomed, I'm sure they'd do far better in a pond, as I believe them to be one of the larger types, despite them having already experienced a large amount of stunted growth - I would guess they were no more than 15cm long, whereas no doubt they could have grown far larger than that.

 

[Prime Ordeal]

I'm always amazed at what goldfish can tolerate (or should I say suffer!), certainly the accumulation of nitrate (and other toxins) would have stunted their natural growth rate.

As for stocking levels, as long as the tank is well filtered and well maintained then you can have 1cm of fish for every litre, so 80cm in this case. The 'cm of fish' does not include the tail but has to be taken from the adult size and not the size that you buy them at.

Oh and the fish I mentioned above can't all be kept together!