Determining The Bioload Capacity Of Aquarium

[dmac0923]

i was wondering how you can determine the bioload capacity of a 29 gallon fully cycled aquarium?

29 gallon
mixed live and fake plants
aqua clear 70g (300 GPH) HOB filter

 

[Puffdaddy]

The amount of waste a fish produces varies from species to species. Along with many other factors. In short the answer is experience. You got a good filter for your tank so you will be better off that one with less gph.

 

[karmagl]

It's all in the water levels. If your water levels start to get high then you need to cut down on some fish. Some people say there is a different amount of fish for every size tank but thats not true. Fish come in different shapes and sized . Before you do your normal water change test your water first to see what your levels are like.

 

[mark.w.jones]

I seem to remember there being a very complicated calculator at Practical Fishkeepings website to help you work out bioload. In a nutshell.

Waste Produced by Fish must = Number of bacteria who can survive on waste​

Both of these factors vary hugely though. Waste produced depends upon the species of fish, the number of fish and also upon what and how much you are feeding them. The number of bacteria present depends upon the type of filtration you have in terms of media volume, surface area of your media and flow rate through the filter.

In a perfectly stocked tank there will be a balance between these to. If you overstock, then the waste your fish produce will exceed the amount that can physically be utilised by your bacteria because at some point there will be no more room for any more of them to grow.

On top of this are other contributary factors such as tank temperature, maintainence routine, whether you have live plants etc.

Anyway, there are so many factors that is is next to impossible to determine the exact number / species of fish you can have. Most members here quote 1" of full size fish per US gallon of water. This falls within a safe bioload for the majority of fish species you may own. Obviously there are exceptional fish which produce a lot more waste for their size than others. Goldfish, oscars, piranas are a few and for them, here the 1" per US gallon rule doesn't work.

A bit rambling I know but I hope i've helped somewhat

 

[rdd1952]

As mentioned, the best rule of thumb for community fish (tetras, corys, danios, etc) is 1" of adult fish per gallon. More importantly in figuring bio-load is probably the filtration you have. The minimum filtration is a filter that will process your water 5 times per hour. So for your 29 gallon tank, you need a filter that's rated at least 150 gallons per hour. If you run a filter that's rated 300 gph you could keep a higher stocking level since the filter would be able to process the additional ammonia but you would have to do water changes more often to reduce the nitrates as they will build faster as more ammonia is processed.

As someone's signature used to say (maybe still does but I haven't been active for a while) "Under stock and over filter." You'll never go wrong in that situation.

 

[Miss Wiggle]

the " per gallon rule is good for starters, but to check how close to your stocking you are check do your weekly water change then test your nitrate an hr later. test it again 7 days later just before the next water change, if it has increased by 40ppm then it's pretty much perfectly stocked, if it's over that you've too many fish, under that and you've room for more. bear in mind when your fish are young you should be under to allow room for growth

 

[dmac0923]

thanks guys thats what i was looking for!!!