Low KH - baking soda OR crushed coral?

[Neptune555]

I have a planted 55 gallon tank with power compact lighting very established. My tap water has very low KH. My PH dropped to an unsafe level... 5.0 and I did water changes to remedy. I have added some tetras so I need to ensure my water remains stable for them.

Current Tank Conditions: PH 6.5 - 7.0 / Kh 1 - .8 / Nitrate 0 / ammonia 0.
Tap Water: PH 7.0 / Kh 1 - .8

Should I add crushed coral to a filter or Arm & Hammer baking soda to add KH - carbonate hardness? What is more stable?

Neptune

 

[wesleydnunder]

Calcium carbonate is a better buffer. Have to be careful with water changes as large partials with straight tap can cause the KH to drop rapidly, then take a while for your crushed coral to dissolve. I've seen folks with extremely low KH do calcium carbonate addition with a reactor system similar to a SW kalk reactor.

Mark

 

[fishorama]

I've done both separately but like Mark said, big water changes can cause big swings. If you do both coral in the filter & add baking soda on refills it works with less variation. I don't recall the amount of sodium bicarb I used to get KH to ~3-5 GDH. I used ~ 2 TBSPs cc in a piece of panty hose for a 75g.

With only bicarb the fast growing plants would zero out the KH between weekly WCs. So if you try it maybe dosing 2x/week might be better. (I'm not good at remembering to dose anything so my tanks are always low on whatever, oops). Start with 1/2 teaspoon or so & see how much that changes KH then test again in 3 or 4 days. It won't take long to figure out how much & how often.

Depending where you live, your KH may vary seasonally, mine did.