My tap water’s pH is pretty high, but once it gets in my tank it lowers to about 6.4-6.8. I have two fantail goldfish and I’ve read that they thrive in pH’s of 7.4-7.8. In the past month, I’ve used baking soda to bring up the levels, but as of today, they’re back down to 6.6ish. I need something that will bring up my levels long-term, but will not exceed 7.8. What should I do?