Pure R.O. additives

[Jdmcfast]

What is the best economical option for additives for pure R.o. water. My tap water has been so inconsistent I've been trying pure R.O. in some tanks I've used seachem's fresh trace and like it. But have not been able to find a good source at a good price and $ 11 for 500ml is too expensive for a semi permanent option. I was wondering if maybe I could buy the dry trace minerals like from a dry fertilizer supply but can't find much info on that.

[LizStreithorst]

Personally I've never had a problem using straight unconstitued RO.  I know a few other people who do as I do and have had no problems.  BUT it does go against conventional wisdom.  If you want a cheap alternative to the commercial products use this:  3 parts calcium sulfate (gypsum) 1 part calcium chloride and 1 part magnesium sulfate (Epsom salts).

[Jdmcfast]

Personally I've never had a problem using straight unconstitued RO.  I know a few other people who do as I do and have had no problems.  BUT it does go against conventional wisdom.  If you want a cheap alternative to the commercial products use this:  3 parts calcium sulfate (gypsum) 1 part calcium chloride and 1 part magnesium sulfate (Epsom salts).

Thanks liz. How exactly do u dose this? Do u see any difference in growth with pure R.O.?

[BillT]

I use RO water as source water for several water systems.

I add synthetic ocean salts (usually reef salts or instant ocean) back to the RO water to a conductivity of 500?S. This is the general strategy used in zebrafish labs, mostly because it is easy I think. Different labs use different conductivities ranging from 500 to about 2000?S.

To add some buffering and carbonate (required for biological filter functioning because the bacteria use 7 carbonate molecules for each ammonia molecule processed) I usually throw in some small sized (sugar size I think) aragonite. This will dissolve if the pH is below 8.3 and the rate it dissolves will decrease the closer the pH is to 8.3, so it is kind of self regulating. Plus I don't add much at a time. Other people add sodium bicarbonate but this can drive the pH up quickly and can more easily be blown off from the water by aeration.

I bought a bag of aragonite several years ago and am still using it. I get a box of salt once or twice a year.

Out of curiosity, I looked p the pH of a Mg sulfate solution which is supposed to be about 6.0, and calcium sulfate which is supposed to be about 7.7. Sulfates are among the buffers often found in salt mixes (carbonates and phosphates).

Prepared fish food adds significant amounts of chemicals to the water also, especially phosphates which are another buffer and a component of fertilizer for plants and algae.

[LizStreithorst]

Thanks liz. How exactly do u dose this? Do u see any difference in growth with pure R.O.?
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I'm sorry but I slam don't remember.  It's been a long time since I've used it.  You will have to get a good conductivity meter and experiment.  What I do these days is use pure RO for breeding.  Once my fry free swim I do WC with straight aged tap.