Fancy Goldfish Water issues

[JTimmins]

Hi guys, I am new to the site - I am always reading threads, but have never really had an issue that I can't sold/research and work out before.
I have been in the hobby 15 years, alway tropical aquariums - anything from 10l to 600l tanks.

I have recently purchased fancy goldfish, my first coldwater fish since being about 6 and winning a goldfish at the fair (how naive I was!). There are currently 4 juveniles in a 42 litre tank - obviously nowhere near enough, but with a 360 litre tank on the way, very delayed because of COVID 19, this was just a temporary measure.

Now I am having a real issue with the water. One of the fish caught himself on some driftwood, and had a sore on his side. I treated the water with PIMAFIX - something I have used lots in the past for similar issues, and which normally clears something like that up very quickly.

However, on this occasion, it made the water cloudy. The water got cloudier, and greener, as the week went on, so I eventually did a 40% water change.
Now by this point, fortunately the black moors scrape had cleared up, but the next day, the tank was green and cloudy again. I left it another night, thinking it needed some time to clear, and I woke up the next day, and I could hardly see the fish.
I researched lots, and guessed it was an algae bloom, which I have not had before. Research suggested water changes might back the bloom worse, so I tried to leave it, but it just got greener and greener.

Eventually i went to my LFS and got the water tested - water quality was exactly where it should be, absolutely no issues at all. The guy sold me some Seachem clarity, and told me to try it. It did not work at all.

So now I'm stumped. Water changes help for a few hours (obviously, as I'm essentially replacing green water with fresh), but then it clouds up again. I am conscious not to water change too often, as it is a pretty established tank. Of course I am expecting the upgraded tank size, so obviously I appreciate this is not a realistic tank option for much longer.

One thing I've been wondering, is we are experiencing extremely hot weather at the moment, could that be affecting the water?

I have hopefully attached some photos, of it at varying stages...but it did get a lot greener than any of those photos show.

Thanks so much in advance, I really appreciate any thoughts or advice.

[Autumnsky]

Overfeeding, too much ammonia from fish and wasting food, and light cause the green water /algae to grow,

The cloudy/milky bacterial bloom is caused by the same thing of the ammonia food and waste.

Water changes to help remove the things causing the problem. Phosphates can cause trouble.

Sometimes foods are high in phosphate.

You might try some Phosguard and or Purigen.

Using a floculating / particulate binding product. Like Clarity.

And maybe the Stability helped and you just had too much happening in the tank .

You already know the basic answer here, and that is that these guys need a bigger tank asap.

Suggested filtration of 10 times or more per gallon per hour.

Beneficial bacteria to process the waste. Plants.

Alternatively you could remove fish to a bucket - plants to a vase or something(maybe do a peroxide treatment for the algae. Sanitize everything and start over bare bottom and use the BB additives and do your fish in cycle.

You could black out the tank too. So many ways to go.











Nitrates are probably up too. One way to deal with this is gets lots of stem plants to help the processing of nutrients.




A UV filter is often used to help in this situation for the green water.