Hi
our O beats himself up quite alot and often has gash marks on his head, which heal really quickly, he's got one that appeared a few days ago which is a white circle, and I was concerned it might be start of HTH

On Sunday (approx 30-40 hours ago) we changed the filter media - and did tank clean & vacum substrate & approx 20litres new water (tank is 240litres). It looked a bit cloudy yesterday and I was concerned we have disrupted the bio cycle in the tank?
Ammonia was 0.25 - it has always been 0 before
Nitrite was also 0.25 & again have always had 0 reading before.
I forgot to check PH, I will do that tonight, I also dont have a nitrate test, so will get one of those.
Do you think the water quality has been affected by the changes to the filter? what should I do?

thanks

What filter media did you change? You've got to remember that your filter is extremely important, changing your mechanical filtration is one thing, changing your biological filtration is a different ballgame altogether.

If you remove biological filtration thinking that it needs replacing then all you are doing is removing all the bacteria. I would urge you only to change the very fine media that often gets clogged and filthy very quickly, we often call these polishing pads. You really needn't change the course mechanical filtration either, that only needs to be rinsed out when it gets dirty.

If you ever do change biological filtration then don't change it all at once.

It may be a case that you have just removed a little too much bacteria, .25 is nothing to worry about, your filter will soon catch up. It would actually be helpful to know what your pH is though.

Oscars are for ever whacking themselves against the hood or decorations in the tank, it's something that you should expect from time to time. Occasionally they can cause themselves quite nasty injuries. Hole in the head does not appear overnight, it would appear gradually. Why don't you post a photo of your Oscars so we can have a look?

thankyou, we changed all the pads, and one section of the unit has a carbon pad, underneath that we have ceramic things (sorry forget their name!) we only rinsed those. I will check the PH tonight and I will try & take a pic of Oscar, he's a bit uncoperative sometimes with that. I will post it tomorrow with the PH test.

fatbubbles wrote:


Never replace all pads all at once--you should always stagger replacements by several weeks. Give the new pad enough time to build up some bacteria so when you change the other you're not removing massive amounts all in one go.

Also, unless you have enough gunk on the biological media to be causing water flow issues, there's really very little need to rinse them at all. Did you use tank water when you rinsed the ceramic rings?

yes, we did use tap water, I checked the PH last night and it is 7.0 I have taken a picture, will just figure how to upload it

Hi PH was 7 & I've put a couple of pics in my Oscar album, not very good images, but hopefully good enough? I assume you can see from the album?

retest tomorrow and you may find the ammonia has gone back to zero

If you wash the media in the filter in tap water you may have killed some of the good bacteria, hopefully not too much. you need to wash the filter media in old used tank water.

You may have upset your cycle and may have problems with ammonia and nitrite. Test your water over the next few days. If you dont get zero for ammonia and nitrite after a few days then its daily 25% water changes until your filter has cycled again

fatbubbles wrote:


Tap water has chlorine, so you want to avoid any cleaning with that. When doing a water change if you want to clean the filter media just use some of the water you just siphoned out of the tank.. Remember, you hardly ever have to clean the biological media, and pads will last for a long, long time. I only fully replace a pad once every 4 or 5 months...with maybe 2 rinse/cleanings throughout. Generally the instructions on the pad boxes say every 2 weeks...which is absolutely not true. I would make sure you don't use carbon in the pads too, the carbon will lose it's effectiveness within a week or 2 and can actually begin to leech contaminants back into the water afterwards. Best to just use wool or pads by themselves.

yes, you are right, I re tested last night and both ammonia & nitrite now 0.
still concerned about the white mark on his head tho.. I've attached pic

try again with pic

ok so you killed some bacteria by washing the filter in tap water, use old tank water in future

Post a pic of the injury

I tried, but cant get it to upload, interestingly tho it appears to be healing, it looked like a scale grew in the middle of it, now the colour has blended back into his normal colour. But he is behaving very oddly - he is either sitting on the bottom - apparently sulking or staring at his reflection or swimming madly round in small circles? very odd ...