tsd readings

I am guessing he is using a hand held one he just asked if i knew, if he could add coral with high readings

 

It really depends on how "high". Start with softy corals like xenia

 

Tap water is never the answer. It could be OK today and completely different tomorrow.
The simple truth is you have absolutely no control over its quality.

If an RO/DI system is out of the picture then they may want to consider bottled distilled water or check to see if the LFS sells RO/DI. Since they have a TDS meter they can always check its quality.

I would not add any corals without knowing the water quality. Better safe than sorry. His area could use phosphates in the water mains to control corrosion or could use chloramines which do not get removed by simple additives and treatments short of RO/DI.

 

I have a friend with a 10 gallon reef with tap water. Corals galore in that tank. No algae.

 

It is possible but not reccomended.Some areas might have very clean tap water and some may not.It can change day by day and you have no control over it and likely no knowledge of any change in the water quality.