Since this saga is ongoing and I see it is goldfish, I really have to point out you still prolly have too many fish to handle with filtration alone.
He is not as overfiltrated as some of you think..not when you talk goldfish.
Keeping goldies is synonymous with getting a system for tank water change day..because it rolls around often. They are coldwater's answer to the discus......
For an example, this was feb's tank of the month at a goldfish site.
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72 gallon bowfront All-Glass Aquarium
glass top and a triple tube light hood which houses a 48" T-12 Triton, a 48" T-12 Beauty Light, and a 48" T-8 Daylight Plus bulb.
The water stays crystal clear with the help of:
2 Emperor 400 filters
1 System 1 Diaton filter (for clarity)
Rena 400 air pump .
Carbo Plus unit that delivers plenty of
CO2 to 15 different kinds of live Since this saga is ongoing and I see it is goldfish, I really have to point out you still prolly have too many fish to handle with filtration alone. plants
The tank is home to:
2 fantails
2 black moore,
1 telescope,
3 ryukins,
1 pearlscale,
2 tri-colored ranchu,
1 hi-fin banded shark,
4 ottocinclus
4 japanese trapdoor snails.
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That is 9 of the smaller type goldies..the fancy which are no small fry around 8 inches.....a few inches of algae eaters...and one shark.....
This is not to mention the water changes. Or the fact the person admits they are overstocked.
Zap's low
ph = low nutrients and minerals and electrolytes. Your goldies will suck that to zero buffer and you can have wild swings (which doesn't help cycling any)
Really I can't say it enough times; Goldies need every nutrient out of the water they can get and they are a hard water fish as well as heavy oxygen users..specially important fact if they are at temps over 75.
Water has to be a paramount issue if you want them to color up and not develop defects or creeping crud. Fancies will get swim bladder disease if the water quality drops too badly too many times (can't give you the number..it is individual and is dependent of bred-in quality and the other factors like temp, diet or stress)
There are fish you can get away with overstocking if you keep good water husbandry..and there are fish that just won't take less for an answer. Young golds you can get away with pushing the envelope; but once they hit about 4 inches the accomodations better be ready for their adult demands. And I am just talking fancies. Carp bodytypes and koi are a whole nother aminal! And belong in ponds unless you are concentrating on a singular group of fingerlings to control color.
How hard can they be? So many are bred they are feeder fish..
.....yeah..bred IN PONDS.