Help with alk please

[Devildoc]

OK I have a 220 gallon DT, and a 75 gallon sump that runs about 55 gallons of water plenty of flow. My calcium is always at around 440 to 450. Mag is usually 1360 to 1500. I don't dose mag at the moment. I dose when needed brightwell tech code a&b well I still have the cal. But alk is out and I have been dosing baking soda at 70ml a day for two weeks and can't get my alk to go above 8 usually stays at 6.7 to 7.. pH- stays in between 8.1 to 8.4 .never drops below or above. Temp is between 79.9 to 81 depending on the day outside. I mixed 1us gallon or ro/di with a 1/4 cup baking soda.. thinking this might be my issue.. reef diesyst calculations says I need 35.7 teaspoons to reach my dkh of 12.7.. my question is how much ro/do do I need to use to mix it with? Any further information I can give I will be happy to supply thank you

 

[redfishbluefish]

You're making a relative weak alk solution by mixing a 1/4 cup of baking soda to one gallon. I'd recommend upping the baking soda to 1 1/8 cups, just below it's saturation point, to one gallon of water. You can use the BRS reef calculator to figure out how much of this solution you will need. With this calculator, you'll first want to pick, "Alkalinity Calculator." In step 2, enter your total water volume. In step 3 enter your starting alkalinity, your desired alkalinity, and pick "Sodium Bicarbonate Alkalinity Solution,"

This volume will get you to where you want to be. Note, I would not raise alk more then 1 dKH per day. At that point you'll need to figure out your daily requirement, and dose that amount every day.

Hope this helps.

 

[Devildoc]

OK I thought it was because i made it to weak.thank you I will check it and see what I need.. I usually dose half every 12 hours but like I stated above I haven't gotten it above 6 so I could get my daily doses.. this should help thank you again

 

[mike007]

I am dosing the two part and brs Instructions say 2 cups per gallon for alkalinity.

 

[redfishbluefish]

I am dosing the two part and brs Instructions say 2 cups per gallon for alkalinity.

Mike, the difference in what you are doing and what the OP is doing is that you are mixing up SODA ASH (Sodium carbonate), while the OP is mixing up BAKING SODA (Sodium Bicarbonate). Baking soda has a considerable lower solubility factor then soda ash. You would not be able to get 2 cups of baking soda dissolved into a gallon....just won't go. So what you do is make it up at half equivalence. Since 2 1/4 cups of baking soda is equivalent to 2 cups soda ash, you make up a half batch of baking soda by mixing 1 1/8 cups of baking soda to a gallon of RO/DI.

If the OP wishes to make the alk solution even stronger, he could simply measure out 2 1/4 cups of baking soda and place it on a cookie sheet. Put this in the oven at 300 degrees F for an hour, and you would now have approximately 2 cups of soda ash. "Cooking" the baking soda drives off a CO2 producing soda ash. Simply mix this with a gallon of RO/DI and you've got the stuff you're talking about from BRS. On the BRS Reef Calculator, you would now pick, "2 Part Alkalinity (Soda Ash) Solution."

Hope this is clear. Happy reefing!