ph falling thru the floor... crushed coral?

[totalnewb]

Hi all. So my 10G adf tank read ZERO nitrates today!!! Last week at 20! ph fell thru the floor last night and I guess they all died. I use RO water with Kent RO rite. In the larger tank it's not such an issue. Kh a problem. You would think the kent product would accommodate that rather than exasperate it...
Baking soda limited life. roller coaster.
Bought a bag of crushed coral. Know it takes a few days for effects to register and if add too much, ph will skyrocket...
How to start? How much? Also advised seachem alkaline buffer in interim.
Both products new to me. Afraid to hurt my little buddies.
Please advise on usage / quantities / frequency if possible.
10G adf planted (I simply cant believe my nitrates are dead. who cycles with adf?)
29G mixed planted.
neverending problems... pls help before I have loss of life...
I've got to be at work in 4 hours...

 

[Berylla]

I've never had this problem because my water is very hard and alkaline, but I think for the short term, do a massive water change get your PH up. Have you tried Seachem Replenish? Here's the datasheet for it. Compare to Kent and see which one is better:

Seachem. Replenish

I've also read that crushed coral is good to up the hardness (don't know dosage). Also, you could add 50% filtered tap water (even Brita will do) if you are concerned with dirty water. Tap water has minerals that will stabilize your RO. I wish I could help more. Others will chime in.

 

[totalnewb]

Thanks, I'll check replenish.
I actually did a change Monday night, ph was at 7, tds was 120, nitrates were 10. When I posted last night I should have mentioned that. It was 24 hours until the results from first post.
I use ro water as my tap ph is off the charts, (over 10) and it tests with .5 ammonia!!!!!!!!!!!!!!!!!!!!!!!!!! incidentally, the tap kh is really low. stupid water.
Work beckons and there is nothing more I can do until this aft.
Still hoping for some coral advice...

 

[Berylla]

You're tap water is challenging. Need to add more minerals somehow but without breaking the bank. I'd like to know myself regarding crushed coral.