Brown Alge ?

[ansonluna]

Does not useing RO/DI water cause brown alge? And am I correct in saying that RO water is better that TAP and RO/DI is better still...oh no I've gone crosseyed

[Instar]

A maintained RO is great water and should have less than a 20 TDS reading and if its the right kind of membrane more like 12 to 14. This is acceptable water for reefs.

RO/DI when maintained correctly will have a 0 TDS reading and is the preferred water for mixing with all salt mixes. It is not good for a fresh water tank unless additives are used to restore certain things. Its completely pure H2O. This is NOT bottled water from the grocery store. RO/DI from a well maintained unit is what most of us recommend using if you keep salt water tanks.

Tap water is not at all pure; its very high in total disolved solids and may contain all sorts of unpredictable junk not good for many salt mixes or reef life forms and around south Texas will have greater than 400 TDS reading.

All of the above will support the growing of brown algaes known as diatoms. Snails eat that and other encrusting algaes will grow over it. Brown diatoms are the first algae to colonize a tank.