killing Aiptasia

[bertoni]

I'm working on a thread that discusses ways of dealing with Aiptasia. I've been considering the section on DIY chemicals, and was interested in your comments, if any.

In particular, I was interested in what the problem might be when using hydrogen peroxide. Since it's an oxidizing agent, I'd think you'd want to be careful about the total volume, but are there any other concerns?

Also, when mixing calcium hydroxide to water, is it important to add the lime to to water, as opposed to the opposite order?

Any help would be appreciate!


PS: Here's the draft of the chemical section, if you're interested. Each chemical will get its own page, so the formatting isn't very useful right now...



Kalk and pickling lime are calcium hydroxide, which is used by some to supplement alkalinity and calcium in a reef tank. It can also be used as a caustic agent to destroy Aiptasia. First, you make either a paste or a strong solution using RO-DI water. When the calcium hydroxide is mixed into the water, a lot of heat will be released, so be careful! This preparation can be injected into or sprayed onto Aiptasia using a syringe.

Note that this solution will destroy any living organism it encounters, and blobs of the solution, if they form and circulate in the tank, can land on your prized coral, anemone, etc. Also, this approach will increase the pH of the tank and add calcium and alkalinity. All of these secondary effects can be dangerous. Start out with a small amount of solution, perhaps 1ml, and watch your tank's water parameters carefully.

The kalk preparation is also dangerous to you. Be very careful with it. Eye contact is the main danger here.



Lye is sodium hydroxide. The Red Devil brand, if available, seems to work well. You can make a lye solution using RO-DI water. Add the lye a bit at a time to the water and stir. The mixing will generate a lot of heat, so the author recommends mixing small amounts and using heat-resistant containers. Don't add water to lye. When the water comes into contact with the lye, it can boil and splatter.

This solution can be injected or sprayed onto the Aiptasia using a syringe. It will damage or kill any organism it contacts, so be careful. Like calcium hydroxide, it can form blobs that circulate around the tank and cause destruction if they land on a coral or other organism. This chemical will raise the pH and add alkalinity to the tank, so start out with small amounts, perhaps 1ml, and watch your water parameters carefully.

Most importantly, this solution can be very dangerous to you! Avoid any contact with skin or any other part of you. The warnings on the [i]Red Devil[\i] container are quite serious.



Hot water can be injected into Aiptasia. [Experiments to follow]


Vinegar can be injected into Aiptasia. This chemical is safe in small quantities, but it can lower the pH of your water and deplete alkalinity. Some testing should be done as you proceed with your work. [Experiments]




Hydrogen peroxide is an oxidising agent, and can be injected into Aiptasia. [What guidance is there to give on its use...]

[Randy Holmes-Farley]

Sounds like a nice project! :)

Also, when mixing calcium hydroxide to water, is it important to add the lime to to water, as opposed to the opposite order?

No, but it is very important to be careful if it is quicklime (CaO) as it gets very hot when mixed with wtaer as a slurry. Calcium hydroxide does not release that much heat.

Vinegar can be injected into Aiptasia. This chemical is safe in small quantities, but it can lower the pH of your water and deplete alkalinity.

Vinegar won't deplete alkalinity, but it does lower pH.

Hydrogen peroxide is an oxidising agent, and can be injected into Aiptasia. [What guidance is there to give on its use...]

I do not know how much it takes to kill aiptasia, so I do not know how much one must be concerned with adding it. I am also not sure how much one can get into the water column without causing a problem for other organisms. The concern is high ORP, other highly oxidizing byproducts when it reacts with tank water, and the possibility of either the H2O2 or other oxidizing species irritating organisms, especially those nearby.

[Hobster]

I have mixed pickling lime 50/50 with vinegar to kill the little buggers. The lime dissolves real well in the vinegar. Don't know if it is any better or worse. Maybe kills them twice;) Also some folks have mentioned using lemon juice if you don't already have that one on your list.

[jfinch]

My sump was completely covered in aptasia. Really covered! In the hundreds, easily. No way I would be able to individually kill them all and some areas (the ones more infested) were too swift for peppermint shrimp (the shrimp worked wonders in my refugia). I figured that a fresh water bath would kill em. I drained my sump and soaked it in cold tap water for about 1.5 hr. It did kill almost all of them, but I'll be damned if about 5 survived! Next time I'll use HOT water (I didn't have the guts to add bleach :) ).

[thackray]

Randy said:
Vinegar won't deplete alkalinity, but it does lower pH.

Somewhere you showed the initial chemical reactions for vinegar and limewater and discussed the subsequent products but I can’t seem to find it.

Phil Thackray

[Randy Holmes-Farley]

It (and anything else that I could put into an epic about limewater) is in the January 2005 Reefkeeping.

"What your grandmother never told you about lime"

Here are some sections on vinegar and limewater:

Vinegar and Limewater to Reduce pH
The reason that limewater raises the pH of aquarium water so considerably is because of the hydroxide that is added. As described above, the hydroxide can combine with carbon dioxide to form bicarbonate and bring the pH back down. In many aquaria, however, the aeration is not great enough to bring in carbon dioxide fast enough to meet all this demand, and the pH rises. There are several ways to add additional carbon dioxide to meet this demand, including delivery from a carbon dioxide cylinder. Many aquarists, however, choose to add carbon dioxide in the form of vinegar. Many of these choose to add the vinegar directly to the limewater, although if pH lowering is the goal, it can also be added to a high flow area of the aquarium directly.
When vinegar is added directly to aquarium water, the active ingredient is acetic acid. The first thing that it does is ionize to acetate and H+:

6. CH3COOH ---> CH3COO- + H+

Bacteria can then metabolize the acetate to get energy in the reaction shown below:

7. CH3COO- + 2O2 ---> CO2 + H2O + OH-

On balance, the H+ released in (6) and the OH- released in (7) offset each other, and the net addition is simply carbon dioxide:

8. H+ + OH- ---> H2O

9. CH3COOH + 2O2 ---> 2CO2 + 2 H2O

One of the potential side effects of this metabolism is that the bacteria performing this transformation may grow faster because of it. This growth may have positive or negative outcomes. One potentially positive outcome is that as they grow, they will necessarily consume nitrogen and phosphorus, possibly lowering nitrate and phosphate in the aquarium. Another is that the bacteria may be a suitable food source for other organisms.
Potentially negative drawbacks can include reduce oxygen as the bacteria use it to consume the acetate, and the appearance of unattractive bacterial mats in the aquarium (reported by some, but not by the majority of vinegar users).

Vinegar and Limewater to Boost Limewater Potency
Another potentially useful attribute of vinegar is that it can be used to help dissolve additional solid lime into limewater. It does this by reducing the hydroxide concentration in the limewater:

10. CH3OOH ---> CH3COO- + H+

The H+ combines with OH- in the limewater:

11. H+ + OH- ---> H2O

The actual dissolution of Ca(OH)2 is limited by the multiplication product of the calcium and hydroxide concentrations in the limewater as shown below:

12. Ca(OH)2 ---> Ca++ + 2OH-

13. [Ca++] x [OH-] x [OH-] ----> 5.5 x 10-6

where [Ca++] is the concentration of calcium (in moles/L) and [OH-] is the concentration of hydroxide (in moles/L). Consequently, if you reduce the concentration of OH- via equations (10) and (11) then more Ca(OH)2 can dissolve into solution, and still meet the equation (13) requirement.
This would seem like a concern, however, since losing OH- might negatively impact the amount of alkalinity delivered by the limewater. Luckily, this is not the case. While the OH- is temporarily reduced by the acetic acid in the vinegar, when the acetate is metabolized by bacteria, they release it back to the water:

14. CH3COO- + 2O2 ---> CO2 + H2O + OH-

Consequently, one can dissolve additional solid lime into limewater using vinegar.
How much can one use? The more vinegar is used, the lower the pH of both the limewater and the aquarium will be. One reasonable point to shoot for is to add about the same amount of total CO2 via the vinegar as is needed by the lime to form HCO3-. This balance is roughly matched by using 3 level teaspoons of solid lime per gallon of limewater, and 45 ml of vinegar per gallon of limewater. For those aquarists choosing to use vinegar in limewater, these values are a suitable starting point. Note that the pH of the limewater is still quite high, so slow dosing is usually required.
What kind of vinegar should be used? Luckily, cheap distilled white vinegar is likely the best. More expensive flavored and colored vinegars, such as red wine vinegar, will deliver other unnecessary organics molecules to the aquarium, and are best avoided.

[thackray]

Randy,

So when vinegar is mixed with calcium hydroxide it acts like an inorganic acid binding OH- molecules and allowing more Ca(OH)2 to dissolve. Only when the mixture gets into the tank is the bound OH- and CO2 released by bacterial action and the true organic nature of the process is revealed. Clearly the CO2 is not released in the vinegar/calcium hydroxide mixture since that would precipitate calcium carbonate.

Will the acetate molecule show up on an alkalinity measurement? Treated the same as OH-?


Phil Thackray

[bertoni]

Thanks for the feedback! I'm trying to be accurate, and I need all the help I can get!

[thackray]

Bertoni,

Where and when will your article/thread appear?

Phil Thackray

[Randy Holmes-Farley]

So when vinegar is mixed with calcium hydroxide it acts like an inorganic acid binding OH- molecules and allowing more Ca(OH)2 to dissolve. Only when the mixture gets into the tank is the bound OH- and CO2 released by bacterial action and the true organic nature of the process is revealed.

:thumbsup:

Clearly the CO2 is not released in the vinegar/calcium hydroxide mixture since that would precipitate calcium carbonate.



Right. The pH is too high for bacteria to thrive.

Will the acetate molecule show up on an alkalinity measurement? Treated the same as OH-?

Yes, it does. Once in clear tank water at pH 8.6 or less, there is very little of it, but in limewater there is a lot, and an alkalinty test on limewater should be an accurate measure of the OH- present (and any undissolved Ca(OH)2 or CaCO3 suspended in the water).

Thanks for the feedback!

You're welcome. Good luck with the project. :)

[bertoni]

Phil:

Well, I'm actually ordering a bunch of commercial products and testing them, as well as off-the-shelf chemicals, so it'll be at least a few weeks until the work is done. I'm not going to try some conclusive, exhaustive testing by any means, not that I'm really set up to do that in any case, but I want to get a feel for how these approaches work.

I suspect it'll just be a thread on some public forum here.