Hello. I'm not a chemist by any means, just an aquarist who's in way over his head. I have a problem I need to sort out or I think I risk losing my fish. I've been trying to solve this problem myself all afternoon, and If you'll bear with me I'll walk you through it as briefly as I can manage. Any help in understanding what I'm dealing with or even advice on how to fix it going forward would be greatly appreciated.
Until yesterday I had very hard water, at least 300ppm Gh, 300ppm Kh, and 8Ph right out of the tap. I don't measure my TDS, but I know it's high obviously. I say at least, because the water maxes out every test I've ever tried on it, so it could well be much higher on all counts. My landlord has insisted on installing a water softener. My Ph has dropped to about 7.6, which isn't much of a problem. However my Gh has dropped to 0ppm, which is a death sentence for my fish if I continue changing their water with it. Kh seems to have dipped as well, down to around 200ppm.
To compound the problem, from what I understand, the brine solution in the softener removes the calcium and magnesium ions and exchanges each one for two sodium ions. If that's the case my TDS is going to shoot through the roof. That would put me to at least 600ppm sodium ions in my tap water, which from what I can gather isn't even safe for human consumption, much less my fish and aquatic plants.
Am I calculating this wrong or misunderstanding something I've read? Is it a simple matter of raising my Gh with calcium carbonate? I have crushed coral on hand for just that purpose, but I'm not sure it will matter based on my layman's understanding of the issue.
I suppose I should mention the landlord wont permit me to plumb a bypass onto the softener, I already asked about that.