Are you currently baking your baking soda? If the answer is yes, then you'll want to buy Soda Ash (Sodium Carbonate). If the answer is no, then you'll want to buy Sodium Bicarbonate from BRS.

You do not need or want to use both.

Once you start using BRS Soda Ash you wil find yourself in nirvana. It is so much easier to use as there is no baking involved and you can mix it in by hand easily. However, it is pricy and when you run out you do have to remember to order more. I frequently forget and have to bridge my BRS Soda Ash orders by using Baking Soda from the pantry :cry:

Yes, I use baked baking soda, so should get soda ash then.
I totally forget about pH effect. I do water change every two weeks and also test my water every two weeks a week after water change but I only check phosphate, Ca, KH and Mg. If pH raise that high do you recommend dose alkalinity in the night time? I dose 3 big things when lights on.

Remember that you are mixing Sodium Bicarbonate (Soda ash) with water to make your alk solution, so although it will tend to raise the pH of your tank, it should not raise it to unreasonable values. Certainly not to a pH of 10 ! :-)

If you dose a bit at a time the pH spikes should not be an issue. I have a doser that doses a little bit, 8 times a day. Are you just dumping in the alk solution once a day? How much per dose?

I'm using Marine Magic Triple Doser. I dose Ca and KH 10 times a day and Mg at twice a day. I checked my water last SAT when all lights were off and they were at Ca 380ppm, KH 7.7dKH and Mg 1180ppm. My Mg is usually low but all corals are doing fine, so I don't change a dosing rate. I only have a very old pH test kit, so I have not checked yet. Again my corals are doing fine, so I don't think pH level is not critical condition.

I just found KH 1 gallon container was almost empty. It's time to bake again.....

If everything looks good and healthy, and the only issue you are having is what a chore it is to mix up alk, then my suggestion would be to buy a hand blender to mix your alk, or to buy BRS Soda Ash. Do not change anything else :-)

Thanks Kien. I'll look at both and decide which way is better and cheaper.

I just mixed baked baking soda with a hand blender. It worked really good and took only few minutes. Thanks again your info Kien.

I just use piping hot water when I mix my baking soda, it dissolves for me no problem. Put two cups in to my 2 gallon bucket, turn the tap all the way to hot, wait until it's steaming, and put the bucket under the stream. It cools the water down significantly while it dissolves, to the point where I could even use my hand to mix it with the scalding hot water pouring in to the bucket from the tap if it wasn't also the most unpleasantly desiccating thing to do to your skin. I just mix the bucket with a wooden spoon as it fills up, and by the time the water hits the 2 gallon mark the baking soda is always 100% dissolved, and the bucket water is the temp of a nice bath.

I have way more issues dissolving baked baking soda.

I used a large glass bowl in the kitchen sink and filled hot water in there. Also I nearly boiled RO water to dissolve baked baking soda. And mixing with hand blender. It worked really good.