Help pls! Ive had this problem for months! biofilm/algae

[axolotle42]

Hi I've posted about if before a while back but I still have the problem, I've had this stuff in my tank since last year and I just can't get rid of it, it's driving me insane cause it gets really bad and clogs the filter and I've also seem my axolotl eat it a couple of times. I think it's biofilm but I just don't know, its all over the filter, glass, and decor. Pls help, any advice is appreciated
my axolotl seems perfectly fine and healthy and not stressed at all.
ammonia: 0
nitrite 0
nitrate 25
I dont think it's a temperature problem cause its here in all temperatures but just in case the temp is usually 20° or below-which ik isn't usually ideal for axolotls but mine has never showed any signs of stress and is healthy (it's been 23/24° recently (maybe 2 days at most) cause of a heat wave but it is getting back to usual now and he seems fine, the algae or whatever it is got neither worse nor better during this.)
Thank you I've attached pictures buts it's difficult to capture clearly cause the glass is so covered in it.

 

[wolfen]

all tanks will get a certain amount of bio-film in the aquarium which is why people started keeping snails and other clean up crews in the tanks (also because it was easier then continually vacuuming up food waste).
make sure that your filtration is large enough.
keep the water as cold as possible (bacteria and algae thrive in warm water)
15°c - 18°c is the ideal temperature for axolotls and although can be fine at 20°c it can make them more susceptible to fungus etc..
please look into ways of cooling your tank down as I don't think it will be the last heat wave we have over here.