Newbie fish keeper asks newbie question

[Greyland]

Hello everyone, my first post here so I hope I've posted in the right sub-forum.

I'm relatively new to fish keeping, I have made a lot of errors, received a lot of poor advice, and done a lot of research.

Basically my question is two parts - will my fish be okay until I upgrade to a bigger tank? And is my planned tank big enough?

Now for the info...
TANK: I have a 135 litre tank (35.7 gallon) and I have 5 juvenile fancy Goldfish - they are all roughly 1.5 inches long (1 each of Oranda, Fantail, Ryukin, Blackmoor, and Ranchu). I know I need a bigger tank.. getting to that part in a bit. I cannot stress enough how much I have fallen in love with my fish!
FILTERS: I am running 1x 400 litre/hour (105.7 gallon/hour) HOB filter and 1x 200 litre/hour (52.9 gallon/hour) HOB filter. I use filtration sponge, followed by bionoods, followed by charcoal (soon upgrading to Purigen).
AIR: I am running 1x airstone on a 160 litre/hour (42.2 gallon/hour) air pump.
PARAMETERS: Last water test was yesterday - 0 ammonia, 10 nitrates (roughly), 0 nitrites, pH 7.0.

Within the next year I am planning to upgrade to a 225 litre tank (59.4 gallon) tank. Will this be sufficient to keep my babies happy? And provided the water tests continue to be good (I test 3 times a week) should my fishies be happy for the next few months until I upgrade?

Thanks

 

[Fresh2o]

First off, welcome to AA. Glad you found us.
What you described should be fine for now. I think the rule of thumb is loosely 20g for the first fancy goldfish and 10g for each additional one. The most important thing you can do is water changes. There are other substances besides nitrate that can accumulate between water changes. Also, do what you can to preserve the biological portion of your filters while swapping/cleaning the mechanical portion on a regular basis.


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