Macro Algae Care
By Elizabeth M. Lukan to Critter Corner on Monday, September 8th, 2008.By John Maloney of ReefCleaners.org, edited by Elizabeth M. Lukan.
For the most part, macro algae is simple to care for and is a great way to add color and diversity to your tank. No true ecosystem is complete without it, and it is an inexpensive way to design a great looking tank.
Some of the Pros of Keeping Macro Algae:
- Unlike nuisance micro algae, macro algae, (with the exception of caulerpa), is unlikely to spread throughout your tank and cause problems.
- Macro algae filters nitrate from your tank, and benefits overall water quality.
- Macro algae gives your fish the cover they look for in nature, and increases their quality of life. For example, seahorses depend on macro algae and sea grasses for their survival.
- Most macro algae can survive in a tank with lower lighting when compared to corals.
- Macro algae adds dissolved oxygen to your marine tank.
- Macro algae is tough, and can handle temperature and environmental changes better than coral, making it ideal for the beginning aquarist.
Things to Watch Out For:
The biggest concern the aquarist should have regarding macro algae is if the "plant," (macro algae is not really a vascular plant, but the term "plant" is commonly used both in the hobby and in scientific journals), has a tendency to "go sexual." When macro algae goes sexual, it releases spores into the water to reproduce somewhere else, normally because it is dying. This is normally a result of poor lighting. The problem is twofold; extra nutrients from the plant are released into the water which may raise nitrates, but more importantly the plant will respire more than normal.
The nutrients problem is a small one, and if the dead plant matter can be removed, the remaining macros will eat up the extra nutrients and the balance will be restored. On the other hand the respiration is a bit more serious.
Macros give off oxygen during the day, and will release some carbon dioxide at night. This is natural, and not cause for much concern. If the lighting in your tank fails for extended periods of time, or the plants go sexual for some other reason it will respire more than normal and release more carbon dioxide than it would usually release. This can become problematic, as water that is super saturated with carbon dioxide is likely to have pH fluctuations. If the fluctuation is severe, it can cause deaths in the tank.
There are some tried and true ways of dealing with this potential problem. The first and best way is to have your main tank attached to another tank like a refugium or sump that operates on a separate or a "reverse photocycle." Which basically means when the lights in one tank are on the other tank’s lights are off, and vice versa. By having one tank releasing oxygen while the other is releasing carbon dioxide the system will remain in balance. Another way is to try to keep a good current in your tank so that a natural air mixture is achieved. If you are a beginner, you should try to stay away from algae that have a tendency to go sexual (like caulerpa for example). We keep respiration risk evaluations on all the macros we sell, which you can read about in our Growing Guide Section.
Don’t let this potential problem scare you away from trying to keep macro algae. We have had many plants go sexual on us, and our tanks have never crashed because of this problem. This is just one of those things you should be aware of as you build your marine planted tank.
A Word on Using Macros for Filtering and Reducing Nuisance Micro algae:
All macro algae will remove the phosphates and nitrates that can harm your tank, and feed nuisance algae. By competing with nuisance algae, macro can keep the outbreak of this stuff down.
If the tank you are using to filter your system is going to be seen, then by all means get a diverse group of macroalgas and make a display sump or refugium. If you are as addicted to this hobby as we are, you will certainly have fun setting up this new tank. If on the other hand the filtration area of your tank will be hidden from view, you are better of with just some strong filtering macros.
The kingdom of macro algae is broken down into 3 parts, the red macros (the most diverse), the brown macros, and the green macros. As a general rule, green macro is better at filtration than the others, as it tends to be more prolific, and grows at a greater pace than the others. Caulerpa and Chaeto both grow very fast, although as mentioned before, Caulerpa is not without its flaws. Scroll Algae is one of the best at filtering out of the brown macros, and Spider Algae and Gracilaria are the best out of the red macros we have, but neither is as good as Chaeto. Mangroves, (which aren’t a macro, but a true vascular plant), is in our opinion the best at filtration in terms of volume. However, because Mangroves grow up and out of the tank, they should be combined with Chaeto for maximum filtration results. This filtration team is common in nature, as Chaeto is found primarily among mangrove roots.
Chemistry:
Certain macro algae are calcified, which simply means they have calcium deposits. These plants are generally more rigid than their non calcified counterparts. Popular calcified macro algae in the hobby include halimeda and the shaving brush plants. Our Flame Algae, Fire Fern, and Scroll Algae are calcified as well. While they can survive in tanks that are calcium poor, they need calcium to be between 400 and 450 ppm to thrive. Dosing iodine will also help keep your plants alive, and is generally a pretty simple endeavor. Seachem sells a great iodine supplement with easy to follow directions on the back that even the beginner aquarist can use. If you do dose supplements though make sure you test for them. Magnesium, calcium, and iodine levels should all be tested if you add these products, as there effects can grow in a tank and cause trouble for you down the road. However, the most important nutrients for macro algae are nitrates, phosphates and iron.
Here is a useful guide to ideal water conditions for a macro tank, reef systems and systems that use macro algae as refugium species may differ:
- pH: 7.9-8.2
- Temperature: mid to upper 70’s, although 72-86 is what they can handle.
- Salinity: some can handle large swings in salinity, Halimeda monile for instance experiences 4 drastic swings in salinity a day, and does fine this way. However, try to keep your tank close to the standard 1.024, as not all macro algae are so flexible. Neither are all fish for that matter!
- Calcium: 400ppm-450ppm
- Magnesium: around 1200ppm-1300ppm
- Iodine: .4 is the standard
- Iron: Keep it around .1ppm - Ferrous iron is the best, as it is easilly utilized by plants and macros.
- Nitrites: 0
- Ammonia: 0
- Nitrates: a steady amount around 10-5ppm is ideal for macro tanks. If you use macros strictly for filtering, then you probably want them at zero.
- Phosphates: Keep them around.05 ppm. Or at a ratio between 20 and 14 parts of nitrates for each part of phosphate. So in this 20:1 ratio if you had 10ppm Nitrates, ideally you would have .05ppm phosphates.
Lighting:
For best results we recommend using full spectrum bulbs (5k - 10k look best) that are powerful enough to give off 2-4 watts per gallon of water in your aquarium for most macro species. Some sea grasses like turtle grass require more light. While light intensity is measured in lumens rather than watts, it is often difficult to determine the lumens of a particular light source, and watts are a good secondary measure.
Lighting can have an powerful effect not only on the survivability of the algae, but also on its appearance. For example, in red algae, if the alga is going too dark, (that is too deep a red), then it is not getting enough light, and the green chlorophylls in the alga, (alga is the singular for algae, but watch me use it both ways all the time like it doesn’t matter), are being overpowered by the other pigments in the alga. These other pigments are called phycobilins, some of which reflect red, and some of which reflect blue. The red reflecting ones are phycoerythrin, and the blue reflecting ones are phycocyanin.
Now if it is going past a red wine look, it is usually because the phycocyanin pigments are growing to strong, and you are reflecting too much blue light. a little blue, plus lots of red and a fair amount of green looks like dark brown almost. This can be because you have dedicated too much blue light into your aquarium. For best results, always use a full spectrum light source. If you like the look of blue light, try to tone it down a bit, or place the macro in an area where it will receive less blue light.
If your light is too strong, it can cause the green chlorophyll, (present in all algae), to become too strong, and overpower the pigments that give red and brown algae their distinctive colors, turning them greenish or pale. In this case, try to maneuver the algae in such a way that it becomes shaded from the full force of the lighting.
In Closing:
The ideas discusses in this article are simply to give you a picture of the conditions present in the "ideal macro tank." You don’t need to be perfect for macro to thrive, and even we are off most of the time. Macro algae is relatively easy to keep when compared to corals and delicate fish, and we think with proper patience and adherence to some of the more basic rules you will be able to do just fine.
Liz’s Notes: Editing was limited to spelling and grammar corrections and formatting.
Photo Credits: The photos, in order of appearance in the article are: The Halimeda scabra (Money Plant); Red Gracilaria; Red Mangrove; and Scroll Algae. All images were obtained, with permission, at the ReefCleaners.org web site.