I don't see any algae.
HOW DO I DEAL WITH ALGAE BUILD UP IN MY HYDROPONIC SYSTEM?
Answer: The best method is prevention. If you keep the solution away from light, i.e. keep the lids closed and all openings sealed, you can prevent algae from growing. ALGAE HAS TO HAVE LIGHT, TO GROW.
If you already have algae in the system you can remove it with a SCRUB-brush, or use hydrogen peroxide (3ml of 3% H2O2 per gallon of solution) to remove it. If there are particles floating in the nutrient solution, be sure to flush the reservoir and growing chamber with ample water, and then start with a new batch of nutrient. If the problem is severe, make sure you have the algae completely flushed out to avoid the risk of clogging some of the flow lines in the system.
After you use the peroxide, refill the tank with clean water and DRAIN AND REPLINISH AGAIN to rinse it good.
Some info says peroxide will not help or work, and will kill the plants like it kills the algae. Use common sense and don't flood the plants with peroxide, and rinse the tank throughly.
Got Algae?
All hydroponic growers know what algae looks like - it is often green, but can be brown, reddish or black, it clings to channels, gullies or pumps or oozes over the top of damp media. Algae often has an 'earthy' or 'mouldy' smell, is slimey, or gooey, particularly when large numbers are decomposing in the nutrient. It has the ability to block drippers, emitters, pumps, return channels, and heavy infestations can actually 'seal' off the surface of the media or substrate. It can ruin a pump or stop up a feeder tube in DRIP or BUBBLEPONICS SYSTEMS.
The problem with algae, apart from the appearance and smell problems it creates, is not so much that it uses up nutrients from the solution, but as it blooms, dies and decomposes, it removes dissolved oxygen from the hydroponic system. This increases the biological oxygen demand (BOD) on the system and the plant's roots may suffocate from a lack of O2. Decomposing algae may also release toxins as it breaks down and provides a food source for plant pathogenic fungi which may then multiply to high levels in the system. Algae on plant root systems can suffocate the roots, making the plants prone to attack by opportunist pathogens such as Pythium.
Algae, is a form of plant life, it is a natural consequence of exposing water with nutrients dissolved in it to a light source. Where there is no light, algae can not grow, so the most obvious solution to preventing algae growth is to stop light from reaching the nutrient solution where ever possible. Channels should have light proof covers, return gullies also need covers, large media beds can also be covered with either plastic film or a layer of substrate which is designed to act as a 'dry mulch' since algae can not grow on dry surfaces. In aeroponic systems, the root chamber must be light proof and media based pot or container systems can have plastic or rigid collars made which cover the surface of the media. However, even in the best designed system, there is usually somewhere that light will fall on the nutrient - planting holes in NFT, return outlets in channels and tanks are common areas.
Control of algae, once in a hydroponic system can be difficult - most growers tolerate small amounts of algae in the system, provided it does not become excessive and this usually causes no problems. Where algae growth has become thick and widespread, often the best option is to clean up the whole system after crop removal and start again with a clean system.
Some growers add algicide products into the nutrient to kill off algae and there are a number of these products on the market. However, since any product which kills algae, a form of plant life, can also damage young or sensitive root systems, care must be taken with the dose and damage has been known to occur. Algae will also regrow, very quickly after applications of most algaecide products, requiring more and more of the chemical to get good control. In a study carried out in Belgium on Algae control in hydroponic systems, it was found that many of the products tested for control of algae in nutrient solutions (Diazinon, Endosulfan, Propiconazole, Thiram, Ziram, Quinomanid, Irgarol-1051 and Hydrogen peroxide) were either totally ineffective in killing algae, or killed off much of the algae but were also very phytotoxic to the plants and causes considerable root damage. It was also found that dose levels of 50ppm of hydrogen peroxide was requited to control algae, but that this dose was too phytotoxic for young plants, although older plants survived this dose rate. Therefore, careful and selective use of H2O2 could be used on older, more resistant plants, but since H2O2 is a 'biocide' rather than an 'algicide' there is always a risk of root damage.
Other studies have found 'organic' algae control methods such as adding certain 'grapefruit seed extracts' to the nutrient will kill algae without harming the plants - this is a method used in drinking water, fish ponds, lakes etc and appears to work well. There could be the potential, in larger hydroponic tanks to use 'Barley straw rafts' as a means of algae control as has been proven to work in ponds, lakes and other water ways.
However the best method of algae control will still always be prevention of the problem, so excluding light should be the main emphasis in systems with algae problems.
