Basics : Algae

Any discussion on algae should start with some identification, and while there might be hundreds of types of 'algaes', three categories should be enough for us. The easiest to identify is the type which makes your water green, commonly known as an algae bloom. There are a few which are not really algae, but are actually types of bacteria, commonly appearing as a blue-green slime, or brown dust balls. The remaining lot, floating or growing in various nooks & crannies of an aquarium are (for lack of a better word) what I will call surface algae.

Keeping to the 'basic' nature of this site, I won't be going into scientific names or fine details on any of the algaes. I identify the basic category, review potential causes, discuss it's impact on an aquarium, and offer a few general techniques to control or harvest it. True algae is a type of plant, and provides similar effects as aquarium plants on a different scale. They photosynthesize, uses CO2 and O2, consumes nitrogen food products such as ammonia (fish poop), nitrites and nitrates (all nutrients to them), and provide food & shelter for a variety of microorganisms, invertebrates and fishes.

Generally, algae blooms are avoided except when harvesting daphnia and other types of fry food. Further down I list 7 methods to clear an algae bloom. Bacterial growths are generally harmless, but unlike many types of algae, they don't fit well in an aquarium's food chain, so along with their appearance, efforts are usually to eradicate them. The virtues of surface algae varies by application, location, type and quantity, and I talk about various algae eaters.

Algae & other plants (rooted, floating etc) all compete for the same nutrient group (with varying tastes for certain minerals). Plants are comparable to industrial factories. They take longer to get going, but once in operation, they are more effective in stripping the nutrients out of the water (storing or converting them into cellular growth). Algae is comparable to the street corner vendor. They take very little time to set up shop, multiply quickly if needed, and will disappear if the conditions are not suitable. Many hobbyists use this to their advantage, by heavily planting an aquarium to keep the nutrient levels in the water very low (starving the algae). This does work to a varying degree, however whenever there is a change in the balance (ie: some plants removed or the fish-load increased), then there is an opportunity for an algae to establish itself, so the larger the tank, the more effective this strategy becomes (the nutrient levels bounce around more in smaller tanks, and this bounce favours quick acting algae more than slow acting plants).

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Details...

Algae blooms are single cell plants floating in your water to a density that your visibility in an aquarium might be reduced to a few inches. It surprisingly usually has no direct negative effect on the fish. Indirectly, it will effect anything they do visually, as their movement will be more governed by their ability to sense motion, using their lateral line receptors. Feeding, browsing the bottom of the tank, establishing territories and any spawning rituals might all be adversely affected. In a high fish-load, a bloom can be dangerous, as it's consuming oxygen (it's integrated itself into the tank's biology). If the bloom dies off quickly (as a result of chemicals), the resulting nutrient imbalance can also be dangerous (the bloom was a net consumer of ammonia, and a dead bloom is a net source of ammonia).

Rooted plants with low to mid-level leaves will suffer during an algae bloom, from the reduction of light reaching them. Floating plants may be affected by the reduction in nutrients available. Newborn fry generally do very well in blooms, as they provide a good cover (application dependant), and the blooms are a food source for many organisms which the fry eat. If your tank has nocturnal predators (knifefish, catfish etc), then the cover is not to the advantage of the fry, especially with cichlid fry as the parent's ability to protect the fish will be visually compromised.

If you want to have an algae bloom, put a small tank in a window sill. Dropping a piece of lettuce in might accelerate the process. A drop of water from a local swamp will provide a variety of algae spores. I've only dealt with a bloom twice, but I've advised many customers with this problem, and had their feedback on the variety of products I've suggested. There are basically 7 techniques which I'm aware of, to approach algae blooms with. You can do nothing, use a blackout, starve it, chemically kill it, zap it, filter it or coat it. Unfortunately, the reason that there are so many techniques is because of their varying affectivity.

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Do Nothing
One of my favourites, but only because I'm lazy, and with many aquariums, I let some go wild, some are heavily manicured, and the rest are somewhere in between. Algae spores are extremely fast at multiplying to the limits of their food source, and they are just as fast at dying off if they hit a food constraint. Water changes and feeding the fish add to the nutrient mix feeding these spores, however not every mineral or nutrient can usually be replenished, so once that constraint is hit, these spores crash and quickly die off.

My most recent example was a bloom which ran 3 months. It was a lightly loaded tank with mostly Guppies and the plants were all tough Amazon swords, Hornwort and Java ferns, so I used the occasion to see if one of the methods used to control blooms in ponds (barley pellets) could be applicable to aquariums. The barley did not work (which I attribute to my inadequate method of dispersal), and then I left the tank alone for another month, to witness the bloom completely disappear (with no intervention from me) in less than 3 days. With some finessing, you should probably not have to wait 3 months, and starve them out faster. I mention this as a possible method, and it basically is a reproduction of what happens in nature. Some undesirable environmental characteristic comes along and kills off the bloom.

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Blackout
Single cell algae spores are somewhat fragile, and by causing an extended blackout, the cells should starve (no photosynthesis, and very little energy storage capacity). In principal, yes, in practice, ymmv (your mileage may vary). An aquarium provides a warm and steady supply of nutrients, so the spores might outlast your patience. It is worth trying, as it costs nothing, is chemical-free, and can occur naturally in nature. Start by gravel-vacuuming (removes some of the food sources), and a normal clean up of the filter (more decomposing food sources). Wrap the aquarium in a tight cover, unplug your lights, and avoid feeding the fish. While 24 hours is sometimes mentioned in sites, I would go at least 3-4 days. Note that the blooms occur because of 2 conditions. You have the required spores in your water, and your aquarium provided the appropriate conditions. Consequently, if the conditions remain (and some spores survived), then the bloom may return.

Starve it out
A variant on doing nothing above, but more pro-active, is to cause a deficiency in the water which acts as a natural growth constraint. For a plant, a growth constraint causes the plant to stop growing and eventually die back. On an algae spore, a growth constraint has much more immediate effects (death). Research phosphate removers and barley pellets.

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Chemical Kill
The products exist but I have no great fondness for adding chemicals into an aquarium with live creatures. Chemicals are not tested on as many types of fish in as many conditions as we would like to imagine they are. Their effectiveness varies from doing nothing (at one extreme) to damaging your natural plants (at the other extreme). The packing usually states, only works on some types of algaes, and not in all applications. It might work for you, definitely ymmv.

Zap it
Like a microwave, strong ultra-violet light exposure is devastating on single-cell spores (and many contagions as well). The light exposure must be strong enough to achieve the results, either by using a strong lamp or reducing the water flow past the light. While the UV is killing them, they are multiplying in the tank, so too slow a flow rate may not be effective. Having too high a flow rate and the cells are not sufficiently damaged, so there is a balance between flow and intensity. The price of UV is coming down as it moves into pond mainstream, so this option is looking better. UF filters have their downsides as well, typically only used for short durations, like the diatom filter discussed next.

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Filter it out
Anything in the water column can be filtered out. It's just a degree of the filtration media being used (how small a particle can be filtered out). Research diatom filters. Here is the link for Vortex's site. The media will clog quickly and need to be cleaned. It may take more than one application. The downside is that it generally requires a dedicated proprietary filter (which is designed to hold the diatom media), and their operational requirements are different from conventional filters. The up side is that from all reports, they do exactly what they advertise. No chemicals, no disruption to your biological filter (100% mechanical filtration), no concerns with after-effects of dead spores (they are removed).

The term 'water polisher' comes up when removing small particles from the water. Water polishing refers to the smallest size particle which can be filtered to achieve crystal clear water. The ability of any filter to polish water is a function of 3 parameters, media pore size, condition (age) of media and flow rate. Technically water polishing is done by media pore size, but a low flow rate through a well aged filter media achieves the same thing. In this case, the particles become stuck to the filter's sponge as they travel through. I'm told that Hagen's sponge filters and Eheim's canisters use small pore sizes, so their effectiveness at polishing would occur sooner as the media ages. All filters, especially UGFs have polishing capability. I mention this, as an algae spore caught in a filter will be plunged into darkness, thus making an algae bloom less likely to occur.

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Coat it to filter
Algae spores are small enough to travel in & out of a conventional filter. There are products called flocculents which put a coating on particles in the water column. When these spores are coated, their larger size causes them to be caught in conventional aged (slimy) filter media, or in new tightly woven filter floss. Recommended procedure is to fill your filter's 1st stage with filter floss. When the water is clear (and the floss is bright green with algae spores), just throw away the floss. Effectiveness varies from excellent to no perceptible difference. I don't know the conditions which cause it to have such a wide range of results. Algae spores might survive the encounter with a flocculent (they are released when the flocculent breaks down), so it's important to remove as much as possible, throwing the floss away, or cleaning the filter media.

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BACTERIAL
Brown diatoms are often suggested as being caused by low light conditions, so they can be burnt away by high light. Blue-green slime algae (research Cynobacteria), can often be found on coral substrates in African cichlid tanks. Erythromycin and directed water flow are possible cures. All underwater surfaces are coated in a tan coloured bio-film. Bacterial, this is a harmless aspect of underwater habitats.

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SURFACE ALGAE
Our willingness to allow algae in our tanks in part depends on where you live (generally North Americans are far less tolerant of it, while Europeans prefer a more natural look and even try to harvest some types of algae). The North American culture is in part driven by the same marketing hype which promotes antiseptic living with anti-bacterial sprays and soaps. Japan is also a leader in this regard. If you have algae, then you have a food niche which is being filled by a type of plant, which typically arrived with a fish or plant delivery. Identification can sometimes be difficult, colour variants exist of many types, and appearance will be affected by the water's hardness, food supply and light conditions. Some very good generalized attempts at classification were made here, in the thekrib.com, and here at aquaticscape. For a more detailed attempt at classification, this page on Mike's site has an impressive collection of colour photos.

I often have customers arrive at my counter who announces "I have algae", and they are fully resigned to leaving with a basket of products to begin doing battle. This is why I keep all my chemicals and algaecides behind my counter, so I have an opportunity to outline the pros & cons of this new plant which has taken residence in their tank (and reassure them that their fish are not about to die from it).

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• Many types are a food source for fish, either directly through consumption, or indirectly, by harvesting creatures which enter the food chain, benefiting the fish. The is especially true for fry. Many types of fry have a very high mortality rate when raised in tanks which are completely free of algae. For fish which consume the algae, the benefits are fresh vitamins, and a day-long source of food, which better replicates their natural behaviour. Even carnivorous insectivores (bug eaters) like Julidochromis will snack away at certain types of algae. Almost all fish are omnivorous, but some tending to be more carnivorous or more herbivorous. See algae eaters below.



• The appearance can be very natural. A hair algae covering an otherwise nondescript stone can be very attractive as its 'fronds' wave back & forth in the water's turbulence.



• Biologically, it is providing a beneficial function. The extent of this benefit is probably not justification for keeping algae, but the algae should not be removed by the thinking that it is bad for the tank.

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• On the front glass, they interfere with our vision, so unless you intentionally want this to occur (as with spawning of shy fish), the front glass should be kept clean. This also allows the inspection of the tank's contents, spotting problem symptoms before they get too serious.



• As an opportunistic organism, it's growth rate can be quite rapid, overwhelming slower growing plants. Most of us want a balance of flora & fauna, so uncontrolled expansion of anything needs to be kept in check.



• Expansion over rockwork will almost always permanently discolour porous minerals (coral, tufa, lava rock), partly due to the limited cleaners which can be used. Non-porous minerals (slate, river stones, pebbles, glass) are generally easy to clean. Others (granite, sandstone, picture stone etc) will vary in how easy they are to clean. This discolouration may or may not be desirable.



• Expanding across plants such that they interfere with the plant's growth. Very slow growers (Anubius comes to mind) will often get some layer of algae which is typically easy to wipe off the thick leaves. Finer leaves such as from Echinodoras are generally pruned off to remove the offending algae, and limit its growth to other leaves. Very fine plants which develop an algae 'skin', often in sheets, are usually fast growers, so the affected sections are usually older and are just pruned away.



• Hair type algaes which come up from the substrate choking smaller foreground plants, or choking finer leaf plants can sometimes be somewhat effectively removed mechanically, by twirling a toothbrush in them periodically.



• Cosmetics, beauty is in the eye of the beholder. Some moss ferns resemble algae and some algaes left to multiply will give the appearance of a finely manicured lawn, like a foreground plant. Only you really need to know which is which. Don't be prejudiced by what you hear and keep an open mind.

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Algae Eaters
The unfortunate truism is that generally, due to the relative size of the environment, the type of algae you will have is the type no fish wants, because all the good stuff was already eaten. Almost all fish are capable of eating some type of algae, and none will eat every type of algae. The larger the tank, the more diversity you can have, improving your chances that every type of algae has a waiting customer. I listed the common algae eaters I have in the shop, and my limited observations with them. Further below, I've provided links to much more detailed information, on both algae and algae eaters.

• Common plecostomous: Basically an industrial strength algae eater, available in two sizes, too small and too large. Consider that a 6" fish is basically twice the size of a 4" fish (when it comes to consumption). Plecos (the herbivorous ones) generally grow to about 4-1/2 inches (ie: Bushynose or Bristlenose) or over 12" (ie: common plecs, gibbiceps, etc). Both eat quite a variety of algaes, especially if it's green and can be scraped off. With a large enough tank, the Bushynose (along with a few other types listed below) make a good addition. Even smaller tanks benefit from these characters.



• Chinese algae eater (CAE): Excellent algae eater when small, very industrious. When older, has a reputation for attacking larger fish to feed off their slime coat. Works well in certain applications. Note eventual size (big). Available as an albino or gold.



• Epalzeorhynchus (sp): Similar to the CAE, but not as good at eating algae, but also not as aggressive towards other fish. Not bad if Otos and SAE are unavailable.



• Siamese algae eater: Visually very similar to Epal.(sp), but different mouth and diet. Not good at scraping low algae but does a great job at hair algae, which is an uncommon trait with algae eaters. Very well behaved, but also reaches a fair size (5-6"), so some caution indicated. Look for the black horizontal line crossing the caudal peduncle into the tail fin to distinguish from 'false' SAEs.



• Flying Fox: Similar to Epal.(sp) but smaller. Too many fish come under this name Indonesian Flying Fox, Singapore Flying Fox etc so judgements are not very useful.



• Otocinclus: Small but industrious, this somewhat fragile fish is a favourite. It takes many of them to properly clean a tank, but they are fun to watch.



• Nerita sp snails: Slow but steady, always hunched down to escape predators, Neritas do best in harder water tanks (ie: Rift lake Africans).



• American Flagfish: A type of Killifish, these graze on hair algae. Like most grazers, they don't do a very efficient job, but depending on setup, might keep it under control.



• Molly: Often suggested, whatever skills they have, they have kept secret from me.



• Amano shrimp: Another slow scavenger of various algaes which can be sliced to eat. Fun to watch. I'm not sure how effective they are, as it might take many of them to do the job. Sometimes an ounce of prevention goes a long way, so if your tank is shrimp friendly, it's worth trying a few types of shrimp. I think most shrimp have some algae eating capability.

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