Reefer Addict said:
With diatoms you need to be concerned about the 'silicate' levels, since diatoms need silica to build their skeletons.
Very true, and using RO from a store and running it through a cheapo DI column (Aquarium Systems makes one for about $20) will remove whatever phosphate and silicate the DI is capable of taking out.
more from Reefer Addict...
Phosphates on the other hand are what feed hair algae, and those are tough to contain because you add them each time you feed your fish...
The part about phosphates being a result of feeding is true, but ALL organisms that use chlorophylls and/or accessory pigments to make carbohydrates need phosphate as a source of both energy storage (cyclic amp and adp-atp conversion) and as part of their synthesis of cellular organelles and misc other cellular respirations. Phosphate is one of the 3 necessary parts needed to drive aquarium algal growths (Nitrates, Phosphates, Sunlight).
Many algae are capable of absorbing and storing phosphate above and beyond their actual needs (called
luxury consumption) to use during periods when phosphate may be depleted in their immediate environment. These are conjucated forms of inorganic orthophosphate that are stored as granules (polyphosphate) in the cytoplasm of the algal cell. When conditions become such that phosphate is limited, these polyphosphate granules are broken down by phosphatases (both acid and alkaline) and the cell begins to secrete some of these same enzymes into the surrounding environment to release any stored forms of phosphate in the substrate or other local media (some algae live in symbiotic relationships with certain bacteria that liberate phosphates from the substrate when it is available as well.) This is yet another reason to siphon out as much of the nuisance algae as is possible at the end of the photoperiod in order to remove both the nuisance alga itself and whatever nutrients have been stored and/or converted into biomass.
ylmaya: There are much better RO/DI units than what you will find at HD or Lowes, etc for much better prices. Check
Aqua FX aquarium water filters, as well as
www.airwaterice.com. Salifert did make at one time a good silicate test kit, but I have not seen nor used one in quite some time, just take it as a given that most areas will have at least some removable silicate in their fresh water supplies, especially those areas where the water supply is from major rivers.
Good post Reef Addict, especially about the silicates and the phosphate content of feedings, but phosphates drive ALL algal blooms AND the growth of macroalgae and the few vascular (true) plants that exist in marine environments.
jm$0.02w
