Impact of Larger fish on Nutrients

[Treefer32]

I have a 340 gallon, around 20 fish. Most of the fish are 7-8". I had a reefing friend over that was taking a fish off my hands that's been troublesome and he made a comment "All of your fish are huge." My dragon wrasse is one of the smallest at around 8 Inches long and almost 1 inch in diameter. He was a big eater and decent sized. He could lift a one pound rock with his mouth and throw it aside.

Which is why I was getting rid of him. He was going to a fish only predator tank, which is where he belongs!

I've started feeding slightly less because he was a massive pig, eating close to an ounce of frozen food by himself per day.

So, my question is what is the impact of one larger fish on nitrates and phosphates. Assuming less poop, less food in the display, etc.

Is there a way to say each fish of size 10inches could generate as many as 10 nitrates per week? So, 20 large fish generate 200 Nitrates per week. The reason I ask if there's any type of quantifiable data on something so subjective is that I vodka dose to control nitrates. My nitrates average between 20 and 35. Phosphates average between .1 and 2.

Removing a large fish should reduce those numbers by some. Assuming the fish and the food they eat make up 100% of the nutrients, removing 1 large fish should reduce them by 5% if I feed at least 5% less?

My PH is hitting 7.83 at night, due to vodka dosing. So, trying to determine if I can reduce the vodka dosing to increase the ph and get things more in line.

Maybe removing one large fish isn't that impactful. . .

Tank is 340 gallons with 75 gallon sump. Pellet reactor for denitration, Algae turf scrubber for phosphate removal, no water changes, trace element dosing, and skimmer rated for 500 gallons moderate load, and red Sea reef 1200 reef mat.

 

[MnFish1]

I have a 340 gallon, around 20 fish. Most of the fish are 7-8". I had a reefing friend over that was taking a fish off my hands that's been troublesome and he made a comment "All of your fish are huge." My dragon wrasse is one of the smallest at around 8 Inches long and almost 1 inch in diameter. He was a big eater and decent sized. He could lift a one pound rock with his mouth and throw it aside.

Which is why I was getting rid of him. He was going to a fish only predator tank, which is where he belongs!

I've started feeding slightly less because he was a massive pig, eating close to an ounce of frozen food by himself per day.

So, my question is what is the impact of one larger fish on nitrates and phosphates. Assuming less poop, less food in the display, etc.

Is there a way to say each fish of size 10inches could generate as many as 10 nitrates per week? So, 20 large fish generate 200 Nitrates per week. The reason I ask if there's any type of quantifiable data on something so subjective is that I vodka dose to control nitrates. My nitrates average between 20 and 35. Phosphates average between .1 and 2.

Removing a large fish should reduce those numbers by some. Assuming the fish and the food they eat make up 100% of the nutrients, removing 1 large fish should reduce them by 5% if I feed at least 5% less?

My PH is hitting 7.83 at night, due to vodka dosing. So, trying to determine if I can reduce the vodka dosing to increase the ph and get things more in line.

Maybe removing one large fish isn't that impactful. . .

Tank is 340 gallons with 75 gallon sump. Pellet reactor for denitration, Algae turf scrubber for phosphate removal, no water changes, trace element dosing, and skimmer rated for 500 gallons moderate load, and red Sea reef 1200 reef mat.

No - I don't think you can do that with much accuracy. (especially with using 'length'). With weight, you may be able to get a better estimate. I.e. - With x ounces of fish your nitrate/PO4 do whatever, and you dose accordingly.

IMHO - merely testing - and adjusting is the way to go. Sounds like a nice tank

 

[Treefer32]

No - I don't think you can do that with much accuracy. (especially with using 'length'). With weight, you may be able to get a better estimate. I.e. - With x ounces of fish your nitrate/PO4 do whatever, and you dose accordingly.

IMHO - merely testing - and adjusting is the way to go. Sounds like a nice tank

Thank you, that's what I figured, just thought I'd throw it out there. There's other variables too, like the dragon wrasse constantly stirred, dug, and destroyed my 4" sand bed. With him gone, will nitrates settle into the sand bed instead of the water column and will bacteria propogate in the sand enough to impact nitrates? I have no idea what's going to happen and trying to plan for it, is scary. The tank looks the best it's looked since adding the wrasse. I took out around 3/4 5 gallon pale full of frag plugs, dead coral skeleton, and smaller rocks I had glued corals to thinking he couldn't move that rock... Oh but he did... I probably took out 20 lbs of debris from his 3 years of destruction. He was an amazing fish to watch though. So beautiful. Just destroyed anything that wasn't well glued down. He broke a branch of my candycanes off trying to yank the whole thing off the rock. I'm amazed he got a branch to break off. . .

Everything looks so less cluttered and I can actually put corals on the sand without them getting flipped over or buried!

I don't know whether to increase or decrease vodka dosing. So, I'll just keep testing weekly and adjust as things change. I'll probably reduce my feeding by 30% which will have the larger impact anyways.

My biggest fear is that cyano takes over in the sand bed now that the dragon wrasse isn't there to constantly stir the sand. We shall see! Tank has been running 4 years.

 

[Blake Fabian]

If you're not already using it, I'd highly recommend a fleece roller and an algae scrubber. Those things are godsends for me in terms of nutrient control on my heavy stocked 300g.

 

[spsick]

If you're not already using it, I'd highly recommend a fleece roller and an algae scrubber. Those things are godsends for me in terms of nutrient control on my heavy stocked 300g.

Tank is 340 gallons with 75 gallon sump. Pellet reactor for denitration, Algae turf scrubber for phosphate removal, no water changes, trace element dosing, and skimmer rated for 500 gallons moderate load, and red Sea reef 1200 reef mat.

 

[spsick]

Sounds like you’re doing everything right. Only thing I can add is I think a bigger skimmer may be in order. Skimmers are usually overrated and if you have some monster fish you’re probably pushing yours to the limit.

 

[Treefer32]

If you're not already using it, I'd highly recommend a fleece roller and an algae scrubber. Those things are godsends for me in terms of nutrient control on my heavy stocked 300g.

@Blake Fabian I'm curious how many fish you have in your 300? What's considered heavy stocking?

I have all those things, just the scrubber hiccupped. I think due to loss of trace elements. After dosing larger amounts of trace elements my scrubber is almost full of hair algae again (within 3-4 days of dosing trace elements - in larger than usual amounts).