Coralline Algae Is Not Supposed To Be White

Coralline algae in the marine aquarium in my opinion makes the overall appearance much more attractive and natural.

There are some people who dislike coralline algae and each to their own. I have a personal hatred to having any on the front glass and as soon as I spot any out comes the blade to scrape it off!

Coralline algae comes in a vast array of shapes and various shades of pink/purple as well as other colours – there is one colour that it is not supposed to be however and that is white.

Coralline algae when white basically means that it is either dying or unfortunately is actually dead. If the entire area is white then it is dead, however if either the outer or inner areas are white and the rest still has colour then it is dying.

The white colour is basically the underlying carbonate structure of the algae – very similar to a coral which has expelled its zooxanthellae.

So how can this happen?

Quite a number of things really. It could a be a shift in balance of an important element – for example a drop in Kh in the aquarium. It could be due to the light bulbs being changed above the aquarium and the lights are now brighter. It could be the introduction of new lights. It could be a reduction in water flow. It could be not enough actinic light – the list goes on and on.

There will always be some area(s) in the aquarium where an area of coralline algae goes white. This cannot be prevented as things change inside the aquarium. If coralline was once thriving in an area of high water flow and the water flow is changed then the coralline algae may no longer thrive. I would not worry too much about the occasional area of dying coralline algae but if more than ‘a bit’ starts to turn white then this could be cause for concern.

Some aquarists worry when they see small white spots appearing on the coralline algae. In these cases the area could do with some closer inspection as this might not actually be decline it could actually be worms living on/in the algae.

Rather than go into how to prevent coralline algae from turning white I think it may be beneficial to look at how to actually increase coralline algae growth in the aquarium. If you understand what you need to do to encourage growth then you will hopefully see what is missing if some areas start to go white.

So how do you promote coralline algae growth?

First of all coralline algae does not like bright white light but really like actinic lighting. The first thing you want to consider is increasing the amount of hours that your actinic lights are on for. This is very simple to do by simply changing your timers so that the actinics come on one hour or so earlier and turn off later. Another thing you may want to consider and this does depend upon what else you have in your aquarium is increase the amount of actinic light and reduce the amount of white light.

The second thing is that you want to maintain your calcium at around the 400 mark. Coralline algae is a calcerous algae and therefore needs calcium to be able to grow and expand. As the coralline algae is growing it will deplete the calcium content in the water and you will need to add calcium additives or some other type of supplementary measure to keep calcium at this level.

Magnesium is the next consideration. This level should be maintained at around the 1300 mark. Again additives, supplements etc can be added to the aquarium to maintain this level.

Another element and in my opinion the most important one – strong water movement. Coralline algae does appear to grow better in areas of high flow. Have you noticed in other people aquariums that it appears to grow on powerheads, pumps, overflows etc. Water flow – important for corals, live rock etc but also important for good coralline algae growth.

The final aspect and a word that is said in every aspect of this hobby – patience. You will need to be patient as the coralline algae will not grow and colour up overnight. It will grow slowly at first and probably be so small for a while that you will not even be able to see it. Then after a while it will start to spread covering rockwork, pipes, glass etc and in the end, like me you will be scraping it off the front glass as soon as it appears!

There is another area that needs to be covered and that is the actual introduction of the coralline algae itself. Strangely enough it cannot grow if it is not already anywhere in the aquarium. A good piece of premium live rock will suffice as a seed. What I do when I am attempting to make the coralline spread is remove a piece of live rock from the aquarium and scrape it with a scalpel allowing the scraped coralline to fall back into the aquarium. Where it eventually lands it will hopefully attach and grow. Another method that some people do is not use live rock but use what is called ‘live rock grunge’. GARF manufacture and sell this and from what I have heard people have had amazing results. This method is particularly useful if you do not use live rock in your aquarium and have for example home-made rock or another type of inert rock.

The majority of aquarists aspire to having coralline algae which is a really deep purple in colour. It needs to be noted that you cannot pre-empt the colour that the coralline algae will be. You could purchase a piece of premium live rock which is covered in beautiful coloured coralline and over time it turns into a lighter shade. On the other hand you could purchase live rock covered in a light shade and it turns into a deep colour. The colour depends upon the actual parameters in your aquarium, the water flow, the lighting etc. Every aquarium is unique and that is one of the great things about this hobby.

It also needs to be noted that coralline algae is not always a purple/red colour. It comes in a lot of colours – green, yellow etc however a purple colour is normally the dominant one. One colour which you don’t get however is white – well not that I have ever seen anyway!

There are some products on the market nowadays which are designed to accelerate coralline algae growth. One that I have heard of is one called Purple Up Coralline Accelerator – I have never personally used this or any type of these products as I prefer to do it ‘naturally’ and therefore am unable to comment on their effectiveness even though I have heard that they are quite good.

So if the coralline algae in your aquarium starts to go white then basically ensure that all of the above is correct and correct the one(s) which is off the mark.


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4 Comments
  1. thanks for the advice really help me to understand more of my purple algae! A+++

  2. Glad it was of use.

  3. I agree with the above post 100%. One thing indo want to add is that yes, Coralline Algae is somewhat slow growing but not snail slow. With the right elements, you can see growth and changes within days. It will take months maybe even years to achieve the deep crusts that just smoothers your live rock. I learned this that hard way. I try to do things the easy way because im impatient but Corraline algae just takes time and a little effort on your part. First make sure all your parameter are in check! Salinity, ammonia, nitrates, nitites, phosphate, ph, alkilinity, calcium and magnesium are all determining factors to grow healthy strong Coralline. If your alkalinity and magnesium is off the calcium delivery will be affected. You can have perfect calcium levels and if these other 2 are not right you will have problems growing Corraline algae. I saw a posting where someone asked why there coralline alge was not growing but instead turning white. All answers were ALL WRONG! Someone asked if the algae cam in contact with air! I thought that was interesting because how do you transport liverock encrusted with corraline algae without it being exposed to air? A sponge I agree corraline algae, absolutely Not! What you want is to introduce you tank with Corraline algae or grunge. Keep you parameters as follows:
    Ammonia – 0
    Nitrate – 0 ( if you have clams keep between 10 to 20 ppm )
    Nitrites – 0
    PH – 8.4
    Phosphates – 0
    Calcium – 420 to 480 ppm
    Alkalinity – 8 to 12 DKH
    Magnesium 1200 to 1400

    I prefer to alternate between B ionic 2 part solution and purple up every 2 weeks as needed. Also dose with either kent trace elements or seachem. Add iodide and stronium. Take into account that other things in your tank will benefit form this! If you have a UV sterilizer, turn it off. Lightly brush coralline algae spots with a new or very clean tooth brush to release spores. Make sure a power head is in place to blow the spores to other areas of your tank. After all this, your still not done. Now we have lighting! DO NOT USE MH! I see people posting that there coralline is not growing and when they list light MH is in the subject. Resist from using MH. If you have LPS or SPS that need high lighting them limit it to 3 to 4 hours a day. Coralline algae hates with light, even if your MH emit higher blue spectrum its way to high for them. Use these bulbs! Do your homework and dont believe the hype of a seller lol. I can have the crapiest bulbs and I will tell you they emit the best spectrum. Dont believe what you hear, research it! In our oppinion ATI aqua blue special and true actinics are your very best for replicating the very best simulation to 420 nm and 460 nm. This will make the coralline algae growth explode in your tank. Some like the ATI purple but once you see the blue spectrum on their spectrum sheet it clearly shows more yellow and red then blue. This bulb is strickly for tank apperance rather than growing. Your corals will also thank you for these bulbs. I hope that this helps people along with the previous post that had a lot of information. I just wanted to supplement the previous article with more direct information for the new aquarist success in achieving a tank covered in coralline algae! Happy reefing everyone

  4. Thank you Ray for your detailed addition. I read some experience here! As you say it will no doubt help others achieve a decorative aquarium.

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