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Question: Could live sand that was added to the tank over a year ago be the cause of red, green/black and hair algae

I doubt it honestly, but then there may be some organic material in that sand and that organic material is dying off, giving rise to dissolved organic material (DOC) and small amounts of PO4 and SiO2, just enough though for algae and diatoms to grow

Additionally, and this is a controversial topic, if you are running a plenum on that tank, the amount of nutrients that accumulate in the plenum may start to leach back into the tank by osmosis, or through the sides of the grids that support the sand, close to the tank panes, if the separation between the plenum and the tank itself is not water movement tight.

When that happens a continuous stream of nutrients enters the tank, and unexplained algal growth starts. This is a difficult situation to remedy as the stream of nutrients is continuous and thus the supply of foodstuff for algae is also.

Again the saltwater library of our web site contains a rather detailed article on this. The Netclub ™ contains an even more detailed one.

There could be another explanation too. Say that you have live rock and that some areas of that live rock are covered with material of organic nature that starts to decompose.

This decomposition lowers the pH in that area. Indeed it goes hand in hand with the production of carbonic acid (carbon dioxide first and then carbonic acid as it mixes with the tank's water).

If, now, in that same area there is precipitated calcium phosphate, this calcium phosphate will redisolve because of the low pH in that area (due to the carbonic acid) and will result in the nutrient necessary for algae to grow in that area.

That is the scenario where you measure your water quality and everything seems fine, yet algae grow in some areas anyway. The reason everything appears to be fine is that the phosphate and silicate are used up immediately in those localized areas by the algal growth that occurs there.

Remember too that what you measure if actually what is left in the water, after the algae have helped themselves. If you keep that amount real low, the algae will not have enough nutrients to survive and their numbers will start to go down. Eventually all of them disappear because the nutrient level is too low to sustain any growth.

The above expalanation could very well apply in that case. The key therefore is to keep the rock and its pores and crevices clean at all times so that this scenario cannot occur.

This is done mainly by creating a lot of current and turbulence I should say. Such high current prevents the rock from loading itself and prevents the formation of areas where this could happen. Preventing the redisolving of phosphates into the water in localized areas, prevents the growth of undesirable algae in those areas, and in the tank in general. Current and turbulence are more important than we think.

Question: is there any reef safe critters that will eat bubble algae(valonias) Some herbivores do but IMHO Valonia, one example is the Red Sea desjardini Tang. It would appear that the Indo-Pacific variety of this Sailfin Tang does not consume this bubble algae.

Valonia is best removed with tweezers as soon as one sees it appear and before things get out of hand. Be careful not to crush them, as when you do you add plenty of spores to the water and new ones will start to grow in other areas and you will have a larger problem than you started with. AT

Question: What is the cause of cyanobacteria?

That would be impossible to answer in this small amount of time. In short, however, when organic levels (DOC) or dissolved organic carbon starts to build up in the tank and that goes combined with the right temp and the right pH and the right lighting certain types of cyanos appear. Their growth can be real slow at first, and spotty. Soon though you have them everywhere. Your best bet here is to go to our web site's saltwater library and read the articles that I have posted (there are at least 4 or 5 long and detailed ones). AT

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