Water Stats - Help Please

[KathyM]

I have a well cycled tank (for months now) which has been clear of nitrite and ammonia readings for a LONG time.

So you can imagine my surprise today when I've done a test and got this:

pH: 6.4
Ammonia: 0.25
Nitrite: 0.25
Nitrate: 10

What do I do? I assume this has happened because we put a new filter in to support the other two? Afterwards (day later), we removed one of the established filters, putting media from it into the other established one (it doesn't fit in new one).

I feel I've made a terrible mistake and I need your help to fix this ASAP. Sorry for bothering you again!

OK panic over, phoned BIL and I'm about to do a change now.

 

[black angel]

Will be a spike from the new filter so doing small water changes over a few days to stop it rising any further will help.

 

[KathyM]

Thanks, that's what I did yesterday and will do today. I've noticed the penguin tetras are swimming near the surface, and wondered if their odd behaviour was linked to this or more likely be due to the heat affecting oxygenation? If the latter, should I sling in an airstone (and the other filter) to increase aeration? My tank is well planted, but not massively/heavily.

 

[KathyM]

The fish are more important than the plants, so I slung in an airstone. Just putting a new fuse in the plug of the old filter and then that'll go on too. Penguin tetras are now acting normally.