Yes ANOTHER deadly nitrite spike

[hollyfish2000]

Frank -- in answer to your questions:

I don't test the temperature of the water I'm putting into the tank during water changes. I use the "finger" test myself. Generally speaking, it's likely the aged water is a bit cooler than the water I use straight from the tap. In any event, the FISH are not affected by the water change, either from the aged water or the tap water. The fish are affected by the NITRITE that occurs subsequently. (I also do less than a 50 percent change at any one time.)

As for oxygen, the aged water does have bubblers going, so it's oxygenated. Can't speak for the oxygen content in the tap, but it does get oxygenated when it splashes in the bucket and then when it splashes into the tank. And the tank in question is only 45 gallons filtered by a Fluval 405 and 305, so certainly there sufficient surface agitation. I don't know if a temporary lowering of oxygen would kill a bacterial colony living in, among other places, the filters themselves . . .

One thing I think work mentioning -- there was a slight elevation of ammonia, but that recovers quickly; the nitrite recovers much more slowly. However, the nitrite went back to 0 quickly. Now, I did some drastic things to help the bacterial colony recover, including swapping out a filter from another tank, adding Dr. Tim's and reducing stocking levels. Still . . . it recovered quickly. So that might indicate it was not entirely killed off, only damaged.

Still no explanation for the damage. BTW, I haven't done a water change since!!!! Wonder what my nitrate levels are!!

 

[mchambers]

Wow!

Just to add my two cents-worth here...I'm not sure it'll help your situation, but here it is nonetheless.

The bacteria in aquarium filters (and gravel, and other surfaces of the tank) are living as a biofilm...versus living as free-floating bacteria in the water column (which are there, too, just usually in lower numbers). When bacteria are in a biofilm state, in general, they undergo some pretty drastic physiological changes that make them much more resistant to antimicrobials (antibiotics, sanitizers, etc.) than their cousins are in the water column. This is a reversible state such that if an established biofilm gives off free-floating bacteria to go colonize elsewhere, they become susceptible until they settle down again.

Even on food-contact surfaces, the industrial sanitizers that are used often won't affect more than just the surface of a happy biofilm unless you physically remove it (by scrubbing) and allowing the sanitizer to sit on it and have decent contact time with the microbes.

Bacteria are hardy little buggers. I regularly do large water changes AND vacuum the gravel AND clean my canister filter all at the same time. And, (I know I'm going to get harassed for this) I never rinse my sponges in tank water....I use tap water <gasp>. Now, I'm not trying to say that everyone should do this...I think it's situation dependent (if it aint broke, don't fix it). Also, if I plan well enough, I try to alternate between cleaning sponges and the canisters so that just in case I do some major harm, I've got backup still functioning till the other recovers. Yes, I am killing a lot of bacteria in my filter when I do this, but there are a lot still in there to continue on. Aging biofilms go through their own refresh process as well...parts will slough away from the surface, giving it a chance to re-grow.

That being said, I think that it is possible to do things that really harm your biofilm, and not all biofilms are made up of the same bacterial species or strains. What works for me now may not work for me next month if the city alters my tap water parameters, and may not work for you at all.

I love it when you talk microbiology!

Seriously, this is great stuff.