When does too many fish overload your biofiltration.

  • We are currently upgrading MFK. thanks! -neo
packer43064

packer43064

Jack Dempsey
MFK Member
Jul 10, 2008
3,308
3
38
36
Ohio
Okay I was thinking of this and wondered what would happen. Maybe you all can help.

Let's say you have a 100 gallon tank with three 12 inch Oscars and at the end of the week the nitrates get to 40ppm and the filtration is 2 FX5's. What if the fish were doubled now with six 12 inch Oscars and 4 FX5's and at the end of a week the nitrates were still 40ppm now. Of course normal 50% water changes would take the nitrates lower but at the end of the week it would be the number I have said,which is very hypothetical.

if you keep doubling your filtration and keep adding more fish will this ever get messed up. What if you had twenty-four 12 inch Oscars in a 100(Yes I know, absolutely crazy but for sakes just imagine it could happen) and you doubled your filtration to 8 FX5's, would the nitrates still be at 40ppm if daily gravel vacs and everything was in check?

Another question, is this why these tanks that are filled with all kinds of fish and are completely overstocked are kept in check because of massive filtration? I mean if you did have this 100 gallon tank with 24 Oscars and did daily even perhaps twice a day 50% WC's could the nitrates be kept in check.

I'm just trying to see how these people who keep dozens of fish in a small tank and none even die. I hope it's not too confusing, lol.
 
:nilly:

BACON!!!!!!!!!!!!!!!!!!!!!!!!
 
The water changes are a must.
 
What if you had twenty-four 12 inch Oscars in a 100(Yes I know, absolutely crazy but for sakes just imagine it could happen) and you doubled your filtration to 8 FX5's, would the nitrates still be at 40ppm if daily gravel vacs and everything was in check?
Click to expand...

yes, your biofilter has aerobic bacteria which create nitrates via the nitrogen cycle.

the only way to remove them is through the water changes.

problem is, at that level of biomass, your ammonia and nitrite would be through the roof. the water changes would not be enough to compensate and the bacterial population would not be able to keep up.
 
I'm a fish n00b...

but I think adding 8x the filtration will only convert ammonia and nitrite faster. Unless the filters get rid of nitrates, wouldn't 8x the fish = 8x the end result of nitrates?
 
Another question, is this why these tanks that are filled with all kinds of fish and are completely overstocked are kept in check because of massive filtration? I mean if you did have this 100 gallon tank with 24 Oscars and did daily even perhaps twice a day 50% WC's could the nitrates be kept in check.
Click to expand...

tanks like that survive because the nitrates build up slowly and the fish get used to it to a point. eventually, the level hits a critical level of nitrate and they all begin to die.

sometimes that takes a while, but you will see problems like cloudy eye and popeye long before you have any actual deaths.

the catch is, if you try and put a new fish into one of these tanks, they usually dont make it past 48 hours. the high level of nitrate is a shock as is the lower pH that will be associated with super crowded tanks that aren't water changed enough (aka old tank syndrome)
 
The problem with 8 fx-5's on a 100 would turn it into a whirlpool you'd prolly get the same visual effect as throwing your fish in a washing machine with a viewing window.
Simply increasing filtration at high levels of stock doesn't change the fact that you still only have 100g's of water volume. Filters only convert ammonia and nitrites to nitrates and in a heavily stocked tank with crazy filtration it just means you convert to nitrates faster so eventually the nitrate buildup in 100g would be very fast and very large. The only resolution is water changes.

The best solution would be something like a fx5 for mech and an eheim 2262 with 18l of media capacity which would prolly do the same load and prolly save you 400+ watts of power consumpiton. The the key would be a drip system to change 50-100% of the water every day or something nearly as frequent.

I'd say the most important things to pay attention to with heavily stocked tanks is light feedings and very frequent water changes.
 
Regular filters don't remove nitrate, so 24 oscars = 320 PPM of nitrate at the end of the week (assuming 3 produce 40 ppm each week)

yaaaaaay
 
You must log in or register to reply here.
MonsterFishKeepers.com
Top Bottom