Glutaraldehyde and aquarium

[crazyfishmom]

In freshwater (where OP question is from) gluteraldehyde is marketed as a "CO2 source" by API, Seachem etc.
Because it usually doesn't kill vascular plants and kills off nuisance algae, and breaks down over time, it's promoted as "increasing plant growth" for planted tanks.
It's a pretty deceptive way to describe an algaecide.


The "food for bacteria" is just stating the fact that it is a carbon-containing compound that is degraded over time. So are a bunch of other things. I'm sure many poisons and pesticides decompose over time, so you could call them "food for bacteria" if you really wanted to, but that'd be pretty misleading.

I think part of the concern is that aldehydes in general are not easily used by bacterial species and there’s plenty of other food in our tanks essentially meaning that OP would be adding a potentially dangerous material to carbon dose and wouldn’t really be carbon dosing since most bacterial species in our tanks would not readily use an aldehyde as a food source.

 

[Randy Holmes-Farley Verified Community Expert]

The OP is asking about it as a source of carbon dosing instead of vinegar, vodka, etc.

Yes, I understood that. But there are literally millions of organic compounds, and I see no reason to be considering this one over many others. Hence I was trying to understand why one would want to dose this one.

 

[Randy Holmes-Farley Verified Community Expert]

All things considered, I see no reason to think gluteraldehyde is a desirable choice.

 

[crazyfishmom]

Yes, I understood that. But there are literally millions of organic compounds, and I see no reason to be considering this one over many others. Hence I was trying to understand why one would want to dose this one.

Completely agreed. I think every responder has essentially said the same exact thing.

 

[vahegan]

I have a lot of experience dosing glutaraldehyde in a freshwater tank. The active dose is about 15ml of 2.5% solution per 100 l of water each day. It is mainly used to fight unwanted algae (most usually against the black beard algae, which disappears in some 10 days after starting the dosing), It can also be used in lower doses as a carbon source for aquatic plants, to substitute for CO2 supply into a planted tank (Seachem Flourish was originally developed for this very purpose, then people noticed it has algecide properties too). It does not work against the black beard algae in smaller dosages, and the daily dose can be safely doubled in most cases (but proper aeration is required, especially at night).
I always wanted to try it out in a reef tank - nobody knows what would be its effects if used in similar doses. I suppose it should work similarly against the algae, but whether it will also kill the corals, or what doses would be considered save in a reef environment - this all requires experimental investigation, which I didn't want to do on my main tank and I didn't have a second experimental reef tank. I must confess that I have once accidentally filled an almost full 5 l canister of 2.5% glutaraldehyde solution to top off my tank, thinking it was RO water (I was too tired after a busy day and mixed up the containers). The result was as expected - absolutely everything was dead within hours. But that was at least 1000x exceeding the therapeutic dose for that tank.

 

[MiZuboov]

The "food for bacteria" is just stating the fact that it is a carbon-containing compound that is degraded over time. So are a bunch of other things. I'm sure many poisons and pesticides decompose over time, so you could call them "food for bacteria" if you really wanted to, but that'd be pretty misleading.

It's great that we are already close to the right answer. It remains to understand how much carbon and for how long will be available when adding glutaraldehyde.
How can this be calculated?

 

[MiZuboov]

I dont really understand the question. Why are we talking about gluteraldehyde?

Because I study the products that aquarists use in their aquariums.

 

[vahegan]

It's great that we are already close to the right answer. It remains to understand how much carbon and for how long will be available when adding glutaraldehyde.
How can this be calculated?

"How much carbon" is easy to calculate. Chemical formula for glutaraldhyde is C5H8O2 with molar weight of 100.11, which means it contains 60% of carbon by weight (roughly as much by volume, as its density is 1.06). If we add 15 ml of 2.5% glutaraldehyde solution per 100 l of water, this means we are adding 0.225 g of carbon per 100 liters.
How long it will stay? Up to 2 days. Most of it will be gone quickly when the lights are off, therefore for maximum effect I used to dose at night, so that it would stay in water longer, before it decomposed. The above mentioned 15 ml per 100 l of tank water dose is added daily. We are talking about freshwater tank here, and the dose was effective to fight black beard algae.

 

[Randy Holmes-Farley Verified Community Expert]

It's great that we are already close to the right answer. It remains to understand how much carbon and for how long will be available when adding glutaraldehyde.
How can this be calculated?

What would you calculate? How long it remains in the water? That’s not a calculation but a very difficult experiment.

 

[Randy Holmes-Farley Verified Community Expert]

How long it will stay? Up to 2 days. Most of it will be gone quickly when the lights are off, therefore for maximum effect I used to dose at night, so that it would stay in water longer, before it decomposed. The above mentioned 15 ml per 100 l of tank water dose is added daily. We are talking about freshwater tank here, and the dose was effective to fight black beard algae.

How did you determine the lifetime in the water? That seems to require a sophisticated instrument.

 

[MiZuboov]

What would you calculate? How long it remains in the water? That’s not a calculation but a very difficult experiment.

I want to compare the amount of carbon in 1 ml of glutaldehyde and in 1 ml of Red Sea NO3 PO4 or in 1 ml of vodka.
And I would like to know how long it decomposes completely: 1ml vodka and 1ml Glut

 

[Randy Holmes-Farley Verified Community Expert]

Because I study the products that aquarists use in their aquariums.

Ok. It’s not used in reef tanks and I do not recommend it.

 

[MiZuboov]

Ok. It’s not used in reef tanks and I do not recommend it.

I wrote above that this question is interesting to me only from the point of view of a freshwater aquarium.

 

[Randy Holmes-Farley Verified Community Expert]

I want to compare the amount of carbon in 1 ml of glutaldehyde and in 1 ml of Red Sea NO3 PO4 or in 1 ml of vodka.
And I would like to know how long it decomposes completely: 1ml vodka and 1ml Glut

Amount of carbon is not the critical question since some organics have hardly any usable chemical energy (e.g. formate in AFR) and some have a lot of carbon but are not readily metabolized (hexane).

 

[MiZuboov]

Amount of carbon is not the critical question since some organics have hardly any usable chemical energy (e.g. formate in AFR) and some have a lot of carbon but are not readily metabolized (hexane).

It’s interesting! How much energy has Glut?
Can we compare this parameter in vodka and in aldehyde?

 

[Randy Holmes-Farley Verified Community Expert]

I wrote above that this question is interesting to me only from the point of view of a freshwater aquarium.

Your first post indicated an apparent use in reef tanks. If you have no such intent, then are you asking about using NOPOX in a freshwater tank?

 

[MiZuboov]

Your first post indicated an apparent use in reef tanks. If you have no such intent, then are you asking about using NOPOX in a freshwater tank?

Nope
I want to understand, does glutamate work in a freshwater aquarium the same way (feeding bacteria) as nopox does in a marine aquarium?

 

[MiZuboov]

Nope
I want to understand, does glutamate work in a freshwater aquarium the same way (feeding bacteria) as nopox does in a marine aquarium?

To be even more precise, I want to understand if there is a positive effect of glut on bacteria’s (food or something like that).

 

[JoJosReef]

This has become a rather bizarre thread.

 

[crazyfishmom]

This has become a rather bizarre thread.

OP lost me when it became clear that there was no practical implication. There’s a reason I went into Biology and not Physics. Theories, while interesting, just end up annoying me at some point.