Does sump volume count towards number of fish?

[Discusdude7]

Ordered a 90 gallon tank. Will have a sump underneath (30-40 gallons). My question is that will the added volume of the water from the sump count towards the number of discus I can have in that tank? By the "10 gallon per discus" rule I can have 9 discus in the tank but can I get 3 more if I have a 30 gallon sump? I will still be doing daily/ every other day water changes.

[trungnguyen]

that's a good question. I have been wondering the same question like that. I have 100 gallons tank with 30 gallons sump...let's wait for experts answer that for us.
Thanks for bring it up.

[pastry]

YES

[Wes]

Up to a point. 13 adult discus in a 30 gallon tank with a 100 gallon sump so still a 130 gallons. That would only work with sardines

[dkeef]

Sure does.

[dr.nick73]

I would say yes but before you add the extra fish just make sure the display tank is big enough… for example if you have a 90g tank with 75g sump you could put 12 4-6" discus and be ok but if you had a 75g tank with a 90g sump having 12 discus in the 75 would not work…. always go as big as you can on the display tank

[Discusdude7]

So if I have a 90 gallon tank with a 75 gallon sump I can have 16 fish?

[Wes]

So if I have a 90 gallon tank with a 75 gallon sump I can have 16 fish?

sardines:thumbsdown:

[banks2]

What about a 75 gallon with 30 gallon sump ??
Thanks Dave

[OC Discus]

Maybe there is a square inch rule along with the gallon rule. Does anybody have one?


So if I have a 90 gallon tank with a 75 gallon sump I can have 16 fish?

[lipadj46]

So if I have a 90 gallon tank with a 75 gallon sump I can have 16 fish?

I would say that is way too many.


What about a 75 gallon with 30 gallon sump ??
Thanks Dave

I have 10 adults in a 75 and the are pretty packed in.

[DiscusLoverJeff]

I would think if you have an empty tank, meaning just fish and BB it would be fine to add the sump to your calculations for how many will go into a 90 for example. Now if you have a planted display tank for example I would stick with the tank only rule and max out at 9 or 10.

Remember that with all the other things in the tank it is taking up volume and it limits your space.

[Cichlidcraze]

I would say yes and no. Although the sump will allow for the extra bio-load, fish still need space to swim and sometimes escape the dominant fish. Very difficult when they are packed in like sardines. I would look at a sump more as a buffer to help maintain better water quality.

[Magoo40]

Just confirming that the sump would also be counted in any water / med treatments based on tank voulme ...yeah.

[Discusdude7]

Just confirming that the sump would also be counted in any water / med treatments based on tank voulme ...yeah.

Thanks. I didn't even think about that.

[Trier20]

So if I have a 90 gallon tank with a 75 gallon sump I can have 16 fish?

I have a 90 with 16 adults lol

[Discusdude7]

I have a 90 with 16 adults lol

Adult discus--not sardines right lol?

Does this tank have a sump?

[DC Discus]

Just to mention;

When calculating the sump use the effective capacity and not the overall dimensions, as almost no one runs a sump completely full. I once found out the hard way when dosing salt into a system and kept overshooting the salinity with the wrong calculations. =)

Anytime you add water volume to a system your adding a room for nitrates, thus longer for them to building up. I'm still working out if nitrates have a linear relationship to water volume or if nitrates behave like gases do in water (more quadratic increase or decrease), but I digress.

Cheers,
DC

[Discusdude7]

Just to mention;

When calculating the sump use the effective capacity and not the overall dimensions, as almost no one runs a sump completely full. I once found out the hard way when dosing salt into a system and kept overshooting the salinity with the wrong calculations. =)

Anytime you add water volume to a system your adding a room for nitrates, thus longer for them to building up. I'm still working out if nitrates have a linear relationship to water volume or if nitrates behave like gases do in water (more quadratic increase or decrease), but I digress.

Cheers,
DC

Thanks DC..is there a way to calculate the amount of water in the sump after all the media and Poret foam etc is added?

[SnapshotAquarist]

It does allow heavier stocking for the display up top, but only to a certain extent.

No matter how big the sump is, you cant keep a lungfish in a 10 you know?


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[DC Discus]

DiscusDude7...Sorry for the slow reply... Unfortunately, we do this the hard way and dunk media in large 6-10 liter beakers to get actual volumes (+ or - 10ml), another quick way to accounting for volume of media is the packaging label has volumes too. Most of the time the volumes are not significant for medications, etc. We run a 300 gallon sump with 35 gallons of effective media in it and typically maintain that system to the nearest 1ppt (10-15 ppt) for sturgeon and in Nano reef tanks subtracting for the live rocks become significant.

So I vote for the 8-10 gallon per adult discus as a general rule of thumb. I feel it gives these cichlids room to display fishy behavior, like "social hierarchy". I'm sure tons of people can get more fish than that suggestion, but I always fear disease outbreaks with higher densities. But 12 Discus in a 90 should be great! I had 12 in a 135g and I think another 4-5 fish would have been fine. I actually think the longer rectangular tanks are better for discus than the square ones. More distance can be between fish if they're fighting to cool off. I've seen a very dominate Discus sit in the middle of a square tank and peck at all the rest of the fish, as it was easy for him to get to them quickly, that probably could have been prevented with a long tanks?? Just some thoughts.

Cheers,
DC