Daily Dosing Chaetogro confusion

[Michael.Brock]

I have started auto-dosing my 40g breeder macroalgae tank. I have my Nitrates (calcium nitrate) and Phosphates (sodium phosphate dibasic) set up and I'd like to start auto-dosing Chaetogro (I have seen recommendations to dose Iron instead...but I have no fish currently, so no feeding to add other micro nutrients and the idea of "ghost feeding" seems too vague for me ). Brightwell's site recommends a daily dose of 6 drops/20 gallons/day (love vague units like "drops"...). However, on my recently purchased bottle of Chaetogro it suggests daily dosing of 1.5m/20 gallons and makes no mention of "drops". 1.5ml seems a lot larger than 6 drops (the bottle mine came in didn't have a "dropper" top for me to measure). Does 3ml /day into a 40 gallon tank seem too much?

 

[Euphyllia97]

Always follow the instructions on the bottle, the dilution might have changed :)

 

[EnterName]

I think it's about the first 2 weeks where you add 5mL twice a week, so (2 ⋅ 5mL) ÷ 7d ≈ 1.4mL/d. After the first two weeks you go with 6 drops daily which is like you said, less than 1.5mL.
Source: https://www.brightwellaquatics.com/products/chaeto-gro.php

I would also change your calcium nitrate to ammonium bicarbonate. Ammonia dosing is more efficient as the algae won't need to reduce nitrate back to ammonia before getting the precious nitrogen it actually wants. This reduces the need for certain trace elements that are part of enzymes used for the reduction. Randy's article on ammonia explains this quite well.

 

[Michael.Brock]

Always follow the instructions on the bottle, the dilution might have changed :)

This makes a lot of sense...and it didn't occur to me!

I would also change your calcium nitrate to ammonium bicarbonate. Ammonia dosing is more efficient as the algae won't need to reduce nitrate back to ammonia before getting the precious nitrogen it actually wants. This reduces the need for certain trace elements that are part of enzymes used for the reduction. Randy's article on ammonia explains this quite well.

I considered ammonia but I missed that algae processes ammonia more efficiently, or what advantage that provides if we are dosing daily regardless. I had already ordered the calcium nitrate so went with it. Enough people whose opinion I respect here do dose it to be convincing though!

 

[EnterName]

I considered ammonia but I missed that algae processes ammonia more efficiently, or what advantage that provides if we are dosing daily regardless. I had already ordered the calcium nitrate so went with it. Enough people whose opinion I respect here do dose it to be convincing though!

You'll be perfectly fine dosing nitrate. It works, it's just less efficient from a bioenergetic standpoint, that's all.

Algae first have to use nitrate reductase enzymes (molybdenum-based), then nitrite reductase enzymes (iron or copper-based, I'm not sure which one algae use). Only then do they have ammonia, which they can use directly.

So by adding nitrate you are going straight to the less available nitrogen source. When you add ammonia, you're providing nitrogen the same way nature would before the nitrifying bacteria oxidize it. Any excess ammonia that can't be assimilated in time will still end up as nitrate, and if you don't provide enough, the algae can still use those enzymes to get more nitrogen. Overall though, they have to do "less work" and use less molybdenum and iron or copper. Iron especially is one of those elements that depletes very fast and is recommended for daily dosing even when not growing macro algae. It's an element that can become a limiting factor even in nature.

 

[obanarama]

I auto-dose 10mLs of ChaetoGro a day on a 180g reef tank which has a decent sized chaeto refugium (8 gallons maybe?) The instructions say to shake the bottle before dosing. I didn't want to manually have to dose it so purchased this $25 auto-stirrer and have it set up on an Apex outlet to stir my ChaetoGro dosing container for two minutes before my doser puts the 10mls of ChaetoGro in my tank. I also send in ICP-MS tests every couple of months so I can dial in the ChaetoGro dosing by watching my trace levels. It works shockingly well.

 

[Michael.Brock]

You'll be perfectly fine dosing nitrate. It works, it's just less efficient from a bioenergetic standpoint, that's all.

Algae first have to use nitrate reductase enzymes (molybdenum-based), then nitrite reductase enzymes (iron or copper-based, I'm not sure which one algae use). Only then do they have ammonia, which they can use directly.

So by adding nitrate you are going straight to the less available nitrogen source. When you add ammonia, you're providing nitrogen the same way nature would before the nitrifying bacteria oxidize it. Any excess ammonia that can't be assimilated in time will still end up as nitrate, and if you don't provide enough, the algae can still use those enzymes to get more nitrogen. Overall though, they have to do "less work" and use less molybdenum and iron or copper. Iron especially is one of those elements that depletes very fast and is recommended for daily dosing even when not growing macro algae. It's an element that can become a limiting factor even in nature.

Thanks for the explanation. I'm understanding better why efficiency is important.

 

[Subsea]

I have started auto-dosing my 40g breeder macroalgae tank. I have my Nitrates (calcium nitrate) and Phosphates (sodium phosphate dibasic) set up and I'd like to start auto-dosing Chaetogro (I have seen recommendations to dose Iron instead...but I have no fish currently, so no feeding to add other micro nutrients and the idea of "ghost feeding" seems too vague for me ). Brightwell's site recommends a daily dose of 6 drops/20 gallons/day (love vague units like "drops"...). However, on my recently purchased bottle of Chaetogro it suggests daily dosing of 1.5m/20 gallons and makes no mention of "drops". 1.5ml seems a lot larger than 6 drops (the bottle mine came in didn't have a "dropper" top for me to measure). Does 3ml /day into a 40 gallon tank seem too much?

With respect to micro nutrients, as a generalization, it is only necessary to have enough to maintain growth.
The Redfield Ratio of N:P in phytoplankton (micro algae) is 16:1 and the ratio of N:P in most macro algae (seaweed) is 30:1.

NOTE: It is not necessary to maintain the ratio; it is only necessary to maintain sufficient concentration of inorganic nutrients to be consumed.

With respect to how much to dose, with most trace minerals, more is better than less. To know if your trace minerals concentration are sufficient, I evaluate by observing growth. However, when growth is compromised, and their are no obvious reasons; then ICP testing is warranted to know which elements are missing.

I think this post from Obanarama addresses your scenario quite well.

“I auto-dose 10mLs of ChaetoGro a day on a 180g reef tank which has a decent sized chaeto refugium (8 gallons maybe?) The instructions say to shake the bottle before dosing. I didn't want to manually have to dose it so purchased this $25 auto-stirrer and have it set up on an Apex outlet to stir my ChaetoGro dosing container for two minutes before my doser puts the 10mls of ChaetoGro in my tank. I also send in ICP-MS tests every couple of months so I can dial in the ChaetoGro dosing by watching my trace levels. It works shockingly well.”

 

[Michael.Brock]

I now also have my chaetogro container (a flask) on a stirplate and dosing 3ml/day. Once things settle down and I get into my routine I'll get an ICP test as well. Thanks all for the responses and guidance!