Fungus?

[Sibelius]

Nobody could help me with this in emergencies unfortunately, so I wondered if any of you kind plant experts might recognise what I've got on my heater suckers. Is it a fungus? is it harmful to fish or plants? does it affect water quality? should I just wipe it off whenever I notice any?
it's whiteish/clear, and looks fairly grotesque, when I disturbed the water in taking the heater out some slipped off without trouble, and slightly broke up, but not much, I could catch the sections in a net. The rest I wiped off without difficulty. It was grey/clear out of the water and quite slimy. Almost like soft jelly in the hand. Does anyone know what this is, whether it's harmful, or affects water quality etc. I removed the first load, and more has just started to appear about 2 days later. My water tests all seem fine (pH GH KH NO2 NO3 and ammonia) temp is 25/26 C and CO2 is about 15 ppm. lighting is 2WPG, it's a 5 gallon PFK cube.
I hope these pictures give an idea of what it is.

 

[SNAIL]

Are you using DIY CO2? If you are, I have read somewhere that it's to do with the sodium which acts as a buffer that you add to a DIY mixture. It's all about reaction as far as I can remember and it triggers this slimmy growth.
Just don't use sodium when you make a new batch was the advice. I tried it and it worked. Just remove it when you see it. Fungus looks more fuzzy and fluffy and grows on leftover food.

 

[Liam]

Its in my tanks too, it seems totally harmless and is easy to rub off, the shrimp pick at it and seem to eat it so I guess its nothing to worry about, it seems to stop appearing as the tank gets older,

 

[Sibelius]

Thanks, that makes sense, as it's right next to my diffuser. I use CO2 tablets, which contain some trace elements, so I presume it is the sodium in that. I'm going to switch to DIY CO2 with yeast shortly, so that should sort things out.