0.25+ fish/gallon questions...

[Jdpham76]

I remember seeing a thread awhile back asking number of fish to gallon people here have... Most were 0.15 to 0.2 but looking around here most of the people that post are more like less than 0.5. if someone had a 200 gallon tank at 0.25, that would be around 50 fishes. Has anyone done this successfully? How many cubes are you feeding a day? At that number and variety, I would assume a lot and multiple times a day. What are your biggest issues and where do you buy your food?

 

[ZoWhat]

Fish = bioload = increased #of fish = you better have a HUGE skimmer 5x what's rated for your tank

 

[Gregg @ ADP]

Depends on a lot of variables. The overall # of fish is irrelevant...it’s the biomass that’s matters. What that shakes out to fish number wise varies.

We frequently do what would be considered ‘heavily stocked’ systems, and tend to over-filter them. This has more to do with the fact that we might only get an hour or so a week to work on a system (sometimes less), but still want to be able to deliver what the customer wants with high numbers of fish.

My priority in terms of maintaining a healthy, low nutrient ecosystem is to grow the corals. Once you attain a certain coral biomass (and what that actual # is I really haven’t bothered to calculate), you can lean less and less on fractionation and media as means of removing nutrients. We’ve got some heavily stocked tanks where a good amount of food is added twice a day, there is virtually no algae growth in the tank, and yet the skimmer barely collects. I’ve got one tank with a high fish biomass and is just filled with coral where the skimmer pump conked our several months ago, and I actually thought the corals looked better w/o it running, so I’ve left it down.

 

[Jdpham76]

Depends on a lot of variables. The overall # of fish is irrelevant...it’s the biomass that’s matters. What that shakes out to fish number wise varies.

We frequently do what would be considered ‘heavily stocked’ systems, and tend to over-filter them. This has more to do with the fact that we might only get an hour or so a week to work on a system (sometimes less), but still want to be able to deliver what the customer wants with high numbers of fish.

My priority in terms of maintaining a healthy, low nutrient ecosystem is to grow the corals. Once you attain a certain coral biomass (and what that actual # is I really haven’t bothered to calculate), you can lean less and less on fractionation and media as means of removing nutrients. We’ve got some heavily stocked tanks where a good amount of food is added twice a day, there is virtually no algae growth in the tank, and yet the skimmer barely collects. I’ve got one tank with a high fish biomass and is just filled with coral where the skimmer pump conked our several months ago, and I actually thought the corals looked better w/o it running, so I’ve left it down.

Thanks, that's helpful info. Looks like the best way to approach it is to get a mature tank with corals and them adding fish to it.

 

[ca1ore]

Those kinds of rules of thumb are mostly useless. The ability of a given system to support a particular bioload is a function of many factors as noted. There’s also the aesthetic consideration .....

Keep in mind that most tanks overstate their actual water volume. Your 220 example is closer to 200 of actual gallons of water prior to any displacement. Size of the fish is also a major factor. A 2” damsel may act Iike a fish three times it’s size, but it contributes much less to the bioload than a 6” tang would. My display holds 400 gallons and I keep about 100 fish. Roughly half are 3” or bigger (Naso liturgis the biggest at about 10”) with the remaining half around 1 1/2” (mostly damsels). I feed close to 15 cube equivalents per day (with the occasional skipped day). I have a significant nutrient management syste though, including a large skimmer, ATS and sulfur reactor.

 

[Gregg @ ADP]

Thanks, that's helpful info. Looks like the best way to approach it is to get a mature tank with corals and them adding fish to it.

You don’t have to do it that way. When I set up a reef, as I said, the filtering capacity far exceeds what would be required for the volume. In the first couple of years, we will certainly have a high fish biomass, but the coral biomass is still relatively low.

Fir that period, we lean more on the skimmer, media, water changes, etc. As the tank matures, and the coral biomass keeps increasing, we can then adjust all of those other remediations downward.

It’s just a process. The main takeaway is that you don’t have to go light on fish if your filtration is adequate at the beginning.

 

[Phildago]

I like to keep 0.25/gal and have no issues usually. Sometimes a new shy fish won't make it because they don't ever come out of their shell, but theres no actual abuse that occurs currently

 

[Jdpham76]

You don’t have to do it that way. When I set up a reef, as I said, the filtering capacity far exceeds what would be required for the volume. In the first couple of years, we will certainly have a high fish biomass, but the coral biomass is still relatively low.

Fir that period, we lean more on the skimmer, media, water changes, etc. As the tank matures, and the coral biomass keeps increasing, we can then adjust all of those other remediations downward.

It’s just a process. The main takeaway is that you don’t have to go light on fish if your filtration is adequate at the beginning.

How do you know when you are at appropriate biomass of corals for amount of fish? Nitrate levels? Thanks.

 

[Jdpham76]

Those kinds of rules of thumb are mostly useless. The ability of a given system to support a particular bioload is a function of many factors as noted. There’s also the aesthetic consideration .....

Keep in mind that most tanks overstate their actual water volume. Your 220 example is closer to 200 of actual gallons of water prior to any displacement. Size of the fish is also a major factor. A 2” damsel may act Iike a fish three times it’s size, but it contributes much less to the bioload than a 6” tang would. My display holds 400 gallons and I keep about 100 fish. Roughly half are 3” or bigger (Naso liturgis the biggest at about 10”) with the remaining half around 1 1/2” (mostly damsels). I feed close to 15 cube equivalents per day (with the occasional skipped day). I have a significant nutrient management syste though, including a large skimmer, ATS and sulfur reactor.

Do you dose for corals with an ATS? Or do regular water changes? Still need a skimmer with an ATS? Thanks.

 

[ca1ore]

Do you dose for corals with an ATS? Or do regular water changes? Still need a skimmer with an ATS? Thanks.

What kind of dosing? I run a calcium reactor and supplement alk with a doser. Minimal water changes. Skimmer and ATS are synergistic. You can check my build thread on the monster tank page.

 

[Jdpham76]

What kind of dosing? I run a calcium reactor and supplement alk with a doser. Minimal water changes. Skimmer and ATS are synergistic. You can check my build thread on the monster tank page.

I talked to my lfs and they say that running an ATS would require dosing of various elements because there are no water changes to replenish those elements for corals. Don't know if that is true but it seems logical. The dosing of strontium, magnesium, and trace elements.

 

[ca1ore]

Always take what your LFS says with the proverbial grain of salt. Calcium reactor replenishes a lot of trace elements (basically anything that coral uses to build the skeleton) and I’ve been running that for almost as long as I’ve been running an ATS. Latter, chaeto too, probably requires adding some kind of iron supplement and I do that.

 

[Jdpham76]

What kind of dosing? I run a calcium reactor and supplement alk with a doser. Minimal water changes. Skimmer and ATS are synergistic. You can check my build thread on the monster tank page.

Thanks, I was skeptical of my lfs because I never read anything like that concerning ATS systems but I am not an expert on it. What happens when you have to leave town? Does someone else take care of your tank? I may occasional leave for 1-2 weeks and didn't know how people keep the tank managed during those times.

 

[Gregg @ ADP]

How do you know when you are at appropriate biomass of corals for amount of fish? Nitrate levels? Thanks.

Hmmm...good question. Obviously, you want to maintain NO3 and PO4 levels within the acceptable range for the corals you’re keeping.

I think the most obvious indicator that the coral is beginning to take over in nutrient uptake is that even with a high fish load and the feedings you provide, your skimmer will collect less and less.

I’ve got one tank that’s 300 gal and has a bunch of fish in it. Not sure how many, but a lot, and a number are fairly large. There are 10 cubes a day going into the tank, as well as an auto-feeder adding pellets 3x/day. The skimmer is running wide-open, and after 1 week, there might be 1/4” of fairly thin skimmate collected. At this point, the skimmer is just there for gas exchange/redox. It’s no longer removing enough from the water to really even count as filtration.

I have a tough time even keeping a refugium going on that tank.

 

[ca1ore]

Thanks, I was skeptical of my lfs because I never read anything like that concerning ATS systems but I am not an expert on it. What happens when you have to leave town? Does someone else take care of your tank? I may occasional leave for 1-2 weeks and didn't know how people keep the tank managed during those times.

I have teen sons that keep an eye on things, though most things just run and dosing is automated.