Ok, my ph has always been low in my tank. I didn't know how to raise it until i read something about baking soda on here.
-the ph in my cycling 30 gallon tank has been fine until today. it was 7.5 for a week, and yesterday I did a 30% water change, and it was fine. I tested it just now, and it is at about 6.9. I have about 20 sea shells in the tank as i heard that can help as well. but obviously it's not helpig that much. So, how much baking soda should I add and over what period of time?

i thought shells lowered the ph? oh well we all learn

Sandy, shells are basically composed of carbonate (minerals) so as they add carbonates to the water and therefore raise the KH and the pH. They do it very slowly though and you need a lot of them to have much effect. You're probably thinking of bogwood, which does lower pH.

Grain, you add baking soda a teaspoonful at a time, testing the pH after each addition. Just put it directly into the tank and swish the water around a little to let it dissolve and mix. There's no need to wait like with salt - you can add the teaspoons one right after the other, unless you're changing the pH drastically - like from 6.0 to 8.5 - in which case do it more gradually to allow the fish to adjust. Once the pH has reached 7.4 -7.6, stop. The soda will hold the pH at that level until your next weekly water change. You'll need to replace a little soda each week after you've done the water change - just add and test as before.

Thanks Emma, you're the best!!
-can you think of a reason that Gill's ph dropped suddenly? The ph was fine until today, and the ph out of my tap is 7.5 or even a little more than that.

Here's a calculator I built that will let you put in how much water your tank holds, and how much you want to increase KH and it will tell you how much baking soda to add. It also lets you estimate how much of a pH change you'll get based on your starting and ending KH.

WOW!!! Dataguru that is EXCELLENT! Good job! You should have Koko pin that up or put a link to it on the home page.

:thumbup

Laura

cool, thanks !

-now all i need is a kh test kit

So far, I've used the tetra KH test. It's pretty easy to read. Just count the drops till you see a color change.

Till you get one, I agree with emmahj...just buffer a teaspoon at a time, till pH is up to about 7.6 or so. I predissolve the baking soda in tank water before adding. Test pH again right before you do your partial water change to see if the baking soda you added was enough to keep the pH over 7 between water changes. If it wasn't enough you can add a teaspoon more next time.

1 t of baking soda will get you a 1.7dh increase in KH in 30 gallons of water.