How to dose Hydrogen Peroxide in a saltwater tank

Chances are, if you have landed on this page, you really don’t want to be here. Your reef tank has different ideas though. You may have any number of unwanted types of algae taking up residence, and no matter how many algae eating critters or fish you add, it isn’t working. Your nutrients may be perfectly balanced now too, but algae is a stubborn customer. In this article we will look at how and why of dosing Hydrogen peroxide in a saltwater tank.

peroxide in a saltwater tank

Is peroxide safe to use in a reef tank?

Hydrogen peroxide is a chemical compound expressed as H2O2 containing two hydrogen atoms and two oxygen atoms. When added to water, expressed as H2O, peroxide will break down into both H2O and O. In basic terms this means that peroxide becomes water and increases oxygen in the water when added.

When peroxide is added to a reef tank  the spare O free radical attaches to organic material in the water, oxidising in the process, creating bubbles and oxygen. Crucially, this helps with the control of waterborne algae spores and dinoflagellates by disrupting their life cycle too.

Peroxide, a volatile acidic chemical compound. If not used correctly it has the potential do harm in a saltwater tank. But when used in the correct manner, as I personally have done on many occasions, it can be a valuable addition to your algae fighting arsenal.

peroxide in a reef tank

The use of Hydrogen peroxide to establish algae control is not exclusive to the saltwater hobby. Barley bundles are readily sold as a preventative method of green algae control for ponds. As the barley breaks down it releases peroxide into the water. Pond owners replace barley bundles every 8 weeks.

How to safely dose peroxide in a saltwater tank

Now don’t rush out and buy some barley. The success of a reef tank is reliant control, and the easiest way to control peroxide dosing in a saltwater tank is with precise measurements. Peroxide is not a method you would use to control algae over an extended period of time. It is however, a helping hand when unwanted algae such as green hair algae, brown film algae and even cyanobacteria are evident.

The standard dosage using 3% peroxide solution is 1ml to 10 gallons.

Using this dosage rate, the most immediate and noticeable difference will be the lack of film algae build up on the glass.

The maximum dosage using 3% solution is 3ml to 10 gallons. This dosage rate is reserved for treating dinoflagellates, and again is safe to do so as I can personally testify.

It is important to mention that peroxide will not rid your system of algae. To become algae free, you need to ascertain the cause. If you are experiencing Green Hair Algae read this article, or for Dinoflagellates you can read this article.

Treating live rock with peroxide

It is entirely possible to directly treat live rock with Hydrogen peroxide without causing sustainable damage to the bacteria living within the structure, or to the corals you already have growing on the rock itself.

You can physically remove the rock from your tank. Immediately and liberally spray its surface (wherever the algae is growing) with a spray bottle.  If possible, try to shield your corals from the spray with a paper sheet or similar. On returning the rock to your tank you will notice that the algae is bubbling, with a cascade of bubbles rising to the surface. The peroxide is reacting with the algae (organic matter), which breaks down the integrity of the algae wall. In a matter of days the algae will die back to the rockface.

This is by no means a permanent fix. If you have not established the cause of the algae outbreak, there is a very real possibly it will return.

how to get rid of green hair algae

Can you dip corals in Hydrogen peroxide?

Corals can at times become suffocated by algae, which stunts their growth and even kills them. You may have been unfortunate enough to have bought a coral frag online, and when the coral arrives you see that it may have the beginnings of Green Hair Algae, or any other visible algae. This is the ideal time to ensure you do not transfer the algae into your tank, simply by dipping it in a peroxide solution.

When dipping corals, you should be aware that corals react differently to a peroxide dip, some being more sensitive than others. Thankfully, we can use the guidance below provided by Justin Credabel, a well known and respected reefing nerd.

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Hydrogen peroxide dipping guidelines for corals

For the purpose of coral dipping you should only be using a 3% concentration of Hydrogen peroxide. The dipping duration should be no longer than 5 minutes.

The dilution rate is 1L of tank water combined with the suggested peroxide dose below.

Low 20-40ml
Acropora (tolerance varies widely among species), Montipora, Astreopora, Duncanopsammia, Turbinaria, Galaxia, Cyhpastrea, Alveopora, Hydnophora, Echinophyllia, Mycedium, Oxypora, Tubastrea,

Low/Med 50-70ml
Pocillopora, Seriatopora, Stylophora, Caulastrea, Clavularia, Pachyclavularia, Sympodium, Cespitularia, Yellow Leathers, Pachyceris, Echinpora, Leptoseris, Pectinia, Psammacora

Medium 80-120ml
Porites, Xenia, Brown Leathers, Pavona, Fungiids, Heliofungia,

Med/High 130-200ml
Goniopora, Favia, Favites, Goniastrea, Platygyra, Leptastrea, Blastomussa, Cynarina, Physogyra, Plerogyra, Symphyllia, Sinularia, Corallimorpharian (Mushroom Anemone)

High 210-350ml
Zoanthids, Palythoa, Scolymia, Acansthstrea, Micromussa, Lobophyllia, Euphyllia, Catalaphyllia, Trachyphyllia

Once the coral has been dipped, wash it off with tank water and place it back in your tank. You will notice, during the dipping and afterwards, bubbles rising from the affected area as the peroxide reacts and oxidises.

Coral can be dipped longer in a lower concentrate solution for up to 20 minutes for deep, persistent algae or bacterial infections, or necrotic areas.

Amazon Basics Hydrogen Peroxide Topical Solution USP, 32 Fl Oz, Pack of 1
  • First aid antiseptic (32 fluid ounces); helps prevent the risk of infection from minor cuts, scrapes, and burns
  • 3% hydrogen peroxide formula
  • Paraben and phthalate free

How to treat Dinoflagellates with peroxide

Treating your tank with peroxide for dinoflagellates is part of a much larger treatment program. Unfortunately dinoflagellates cannot be controlled with peroxide alone.

For more information regarding the full treatment regime read our article on treating dino here.

How do you treat Green Hair Algae with peroxide?

As mentioned above, peroxide can be used to treat GHA, but only as part of a wider program. As helpful as peroxide may be in keeping GHA back, it cannot be considered a singular method of control.

For further information on treating GHA read our article here

Does a Söchting Oxydator use peroxide?

The Oxydator is a nifty little device that utilises peroxide, allowing it to slowly react with your tank water over a period of time. In doing so it eliminates to need for manual dosing, and keeps the oxygenated level constant.

For more information on the Söchting Oxydator, read our review here.

Hi, my name is Craig.
I am the owner of The Salty Side.
Firstly, thank you for visiting us. If you have found this article to be informative, and you now have a better understanding of the topic, then my job is done.

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How To Dose Hydrogen Peroxide In a Saltwater Tank