Mini Cycle - Can dirty filter hose (FX5) cause this?

[Ardynas]

I noticed that some of my fish were flashing. Did some testing and found my
Nitrites .25
Nitrates 20
Amm. 0 (slight hint of lime)
pH 7.5

This is an established tank and I've NEVER had any sign of nitrites since I've taken it over (6 months).

My clear hoses from my FX5 raps around the top of this custom 150 tank to the return. The hose is now black from algae in hose. Light is shining down on hose above tank. When I turn on the FX5 after water changes I get a bunch of gunk that comes out. Filter was cleaned about three weeks ago. All bio media left in filter and kept wet.

Do you think this build up of algae could be too much for my BB and cause nitrites to come up (mini cycle)?

I'm thinking of going down to hardware store and getting new hoses and replacing them. Think I will get black hoses so the light can't shine on water (in return hose) and grow algae in them.

I do 50% water changes weekly. Add Prime to tank before re-adding water. Treating for volume of tank. That's about 4-5 cap fulls of prime. Swirl it around whilst adding water. After tank is full I restart filter.

The only other thing I can think of is I've done a couple of 70% changes recently since I had to treat my tank for Camallanus (twice with levamazole).

I'll be doing daily 50% PWC's till Nitrites go to 0.

EDIT: Water has been smelling a little stronger lately than it ever has.

Thanks!

 

[librarygirl]

Hm, not sure if algae can cause spikes like that, I wouldn't think so but not sure. You can get some large pipe cleaners like these: 30 in. Dryer Vent Brush-962510 at The Home Depot and clean the insides of the tubes.

Have you checked your fish? Any missing? A dead fish that's decomposing can cause spikes.

It might also be that the meds took out some of your bacteria. Id' clean the hoses, check for dead fish and do some extra water changes and see if things even out.

 

[Ardynas]

I haven't found any dead fish and none missing yet but will keep looking.

My top hose is so nasty looking I'm going to just replace it (vs cleaning). It's awkward to clean it since it's fairly long. Will rap duct tape over it so the light can't get into it this time. Will check where the hoses connect to the joints and make sure it's not clogging.

Thank you for the response!