Getting Rid Of Nitrate Options

[HappyBuddha]

And what's the reason for max airflow ? I thou BB cannot withstand too high water current ?

I'm quite sure BB can withstand the current generated by a sponge filter. Afterall, the current is relatively weak compared to that inside a typical OHF where many owners often proudly brag about flow rate of thousands of litres per hour!

By over-stocking, maybe we are putting in 2-3 GFs per 100 litres, therefore we would need a higher amount of BB to break down all the waste generated but does this perception/assumption really works ?

You assumed correctly; just cultivate more BB to accomodate an overstocked tank. It implies as you add more fish, all you need to do is add more filters.

Unfortunately, this view is seriously flawed.

You overlooked one fact about the nitrogen cycle. Although you can convert more ammonia (produced by higher fish load) by adding more filtration, the end result is you get more nitrate. Although relatively harmless compared to ammonia, long term exposure to high nitrate concentration (in excess of 10-25 [some say 50] ppm) is said to stunt your fish.

So now with high stock level and more filtration, you need a way to get rid of nitrate. Although you can add plants which takes in nitrate as nutrients, the best way is to change water to discard the nitrate laiden water.

So your answer as to how do hdb dwellers keep overstocked goldfish tank can be sum up as "change water frequently".

You can read up about the accumulative nature of nitrate in the excellent article, My Journey with Nitrates. I hope you will comprehen it fully and come to the conclusion that the way things go, sparsely stocked tank filtered by sponge filters accompanied by diligent water change is the only way to go if you don't just want to keep your goldfish alive but to groom and let it grow to its maximum potential.

And finally I want to add one thing about the need to keep lots of goldfish...

Do ask yourself why is there a need to keep so many goldfish to the extend you know you're overstocking your tank? Wouldn't keeping an amount that you can manage (50-100 litres per fish) be better? I'm quite sure it's fun and exciting to have 45 dogs and puppies in your living room. But I hope you'll have enough time to bath them, feed them, walk them etc. In any case, your 45 pets will probably not be healthy or at their best form becoz you only have that much time and money to spend on your pet.

But of course, I know you'll have better sense and max out at maybe 2 doggies if you live in a flat. Thank goodness for common sense.

So why not apply the same thot when you keep goldfish in your 4 feet tank?