Weird things in my aging barrel

[Zclover95]

So I've been away from the house for the past 2 weeks. In that 2 weeks my fish are fine but my tank is pretty greenish lol. But I went to do a water change last night when I got back and I noticed my power head for it got unplugged (probably my dog) and my digital thermometer fell to the bottom of the barrel. After looking a bit more I noticed there was a film on the surface of the water so I decided my tank can wait another day and I drained the barrel empty and re filled it. After filling it and looking at it again today after about 18 hours there is just a bunch of air bubbles? just sitting on the surface and it looks a little thick on the surface too honestly. My question is, does anyone know if this is just a bacterial bloom from water sitting in it for 2 weeks or could there be something in the thermometer that leaked out?? I'm not sure how they make digital thermometers and I don't want to do my regular 98% WC with poisoned water.. and if it is poisoned, how would I go about cleaning this barrel tonight to get a big WC done by tomorrow?? It's already been 2 weeks since my last WC I dont want my fish to have to wait too much longer I already feel bad about leaving hahaha

Pic related; IMG_20180808_144247.jpg

[brewmaster15]

I think its just bacterial bloom. I'd bleach it.. drain..rinse rinse etc and add dechlor to be sure... you should be good after that.

Al

[Adam S]

Is the barrel new to you? It's probably what Al said, just making sure it's not residue from a used barrel.

[rickztahone]

I used to have this issue. Do you use the dechlorinator straight away when you put in the water? If so, just leave the tap water sitting as is and use the dechlorinator right before a WC. Tap water has chemicals in it that will kill off this type of bacteria naturally. Make sure the water isn't stagnant either. Good surface agitation helps.