Denatured ethanol dosing?

Breadbox · Jun 29, 2022

Due to the very high alcohol tax where I live I've found that denatured lab/industrial grade ethanol to be far cheaper than vodka. However, how reef safe are the various denaturing agents present in these ethanol solutions?

I've heard are some denaturing agents are fine, while others are not, does any know if isopropyl alcohol is safe? I'm aware that nopox contains methanol, therefore it should generally be safe, some of these lab solutions are labelled as "5% IPA", I believe IPA is isopropyl alcohol, so if anyone knows if IPA is Reef safe, I'd appreciate it.

DaJMasta · Jun 29, 2022

It is not safe. While apparently there can be some use for it in a similar vein, it's more toxic than the others, especially to microbes. Also worth mentioning that denatured alcohol varies pretty wildly as to what has been added to it, and many of those additives would not be safe to use - so even if there are types which may be safe, different brands or different factories producing the same thing may not be reef safe, and since it's not made for consumption, there are generally much more lax impurity guarantees.

You're going to be adding so little that I can't imagine the expense being huge.... even at 3x the price I paid for my handle of bottom shelf 80 proof vodka, I use so little it would still easily be the cheapest supplement I'm using in a given timeframe.

Randy Holmes-Farley · Jun 29, 2022

Ethanol denatured with isopropanol is likely safe and I have speculated that is why there is isopropanol in NOPOX.

Do you know for sure that is the denaturant?

Can you get vinegar instead? I prefer it anyway.

Breadbox · Jun 30, 2022

Randy Holmes-Farley said:
Ethanol denatured with isopropanol is likely safe and I have speculated that is why there is isopropanol in NOPOX.

Do you know for sure that is the denaturant?

Can you get vinegar instead? I prefer it anyway.

Randy, if I were to dilute 80 proof(40% Ethanol) vodka into a 5% ethanol solution, does it give the same amount of carbon per volume as white vinegar (5% Acetic acid)?

I'd like to avoid vinegar since the tank's pH is low enough as it is.

livinlifeinBKK · Jun 30, 2022

Have you considered sugar??

Randy Holmes-Farley · Jun 30, 2022

Breadbox said:
Randy, if I were to dilute 80 proof(40% Ethanol) vodka into a 5% ethanol solution, does it give the same amount of carbon per volume as white vinegar (5% Acetic acid)?

I'd like to avoid vinegar since the tank's pH is low enough as it is.

The diluted solution is similar, but different. I think fewer organisms take up ethanol and ethanol provides more energy than acetic acid in vinegar, even for the same number of carbon atoms dosed.

You can dissolve calcium hydroxide in the vinegar to eliminate any immediate pH drop. Averaged over the whole day, ethanol lowers pH just as much as vinegar because they both end up as CO2.

taricha · Jun 30, 2022

fun observation
If you take out a few liters of your tank water and spike it with plenty of NO3 and PO4, split it then add equal carbon amounts of different carbon dosing sources: vodka, vinegar, glucose and then aerate them...
in a few days the bacterial growths in each container are clearly different even to the naked eye. Different structures, amounts of gelatinous material, and overall amounts of biomass.
We grow different things in different ways by which carbon source we pick. How much it matters? No idea

livinlifeinBKK · Jun 30, 2022

If you really can't afford a cheap bottle of vodka, I'd just go for sugar...I actually used to use an AF carbon dosing product that I'm 99% sure was brown sugar mixed with bacteria and it worked great