Advice on changing filters before cycled

[SteveM]

I have a new 75G tank with two 3" goldfish that has been up for about 10 days. Up until yesterday it had just an Emperor 400, now it also has an AC500. My plan is to remove the Emperor, but I am wondering if it might be best to leave both filters on there for a time. I've been testing every other day, and the water has been constant at 0 nitrite, 10ppm nitrate (same as tap), and 0 ammonia, until this morning when there was a slight hint of ammonia (.125ppm maybe - I need to get a better test kit).

At this point is there any bacteria of significance in the old filter, or is it still pretty much "clean"? I really want to take the Emperor off ASAP (for reasons that belong in another thread :x ), but I don't want to disrupt any biological processes that may have started :? .

Any advice is welcome.

 

[tmurphy171]

A few questions. Did you jump start the cycle using some media from another cycled tank? Was the Emperor from another tank? If the Emperor was new it sounds like your just starting the process so switching filters now may not cost you a lot of time. I also switch filters at the very beginning of the cycle without incident.

BTW That being said, the AC 500 may not be enough to handle a 75g tank, either is a Emperor 400. You might want to use both. Between the two you'll have around 900g an hour going thru the filters. Goldfish tanks (I have one) should process water though the filter around 10 times an hour if not more.

 

[SteveM]

The Emperor was brand new, but I did take the bio-wheel from an established tank and "swished" it around in the new tank for 15-20 seconds when I first started. I don't know if this did anything really, but the wheel was a different size so I couldn't run it in the Emperor. All the gravel and ornaments were either new or clean, so there would be no bacteria on them.

I agree on either of these filters alone being marginal once the tank gets more fully stocked, and I will eventually get another AC or add a canister. For now with 6" of goldfish in a 75G, I almost think I could just aerate and do a 25% water change every week or two and be fine, like a big giant goldfish bowl