Limestone question

[btacker]

I was going to use some limestone in my tank, but it has red color areas on it. I have boiled it and scrubed it.

Do I need to worry about the red color ( which I guess is iron? )?

[R.Allard]

when i first started i put allot of limestone in my tank and foundout as time progressed the limestone was breaking down and releasing
other metals and who knows what into my tank causing all kinds of bad alge problems...
i had TDS comming out of my R/O D/I unit at 0.001 and was dripping Kalkwasser at the rate of 3.5 gallons a day so the only thing i could come up with was that the rock was leaching thing into the water.
i noticed that when i took the limestone out of the tank the alge wasnt as bad but still uncontrollable.
HTH
Robert