The fact that it drifted up when you changed something doesn’t mean the absolute values are correctly calibrated. If it’s reading 0.2 high at all points that would be important info.
That’s what’s baffling. I don’t have a refugium although admittedly there’s like an 8”x8” sheet worth of ulva in the display part. I dose a alk mix of 2 parts baking soda to one part soda ash, primarily at night. I don’t dose any alk between 9a to 6p.The fact that it drifted up when you changed something doesn’t mean the absolute values are correctly calibrated. If it’s reading 0.2 high at all points that would be important info.
Aeration might help. Normal outdoor CO2 of around 420 ppm results in pH of 8.3 with reef tank parameters. So the more you aerate, the more it will shift towards 8.3 (which is mostly down if your numbers are right). Or lower if your indoor CO2 level is higher than outdoors.
If you aren’t miscalibeated, you must be adding a lot of something that raises pH because photosynthesis alone wouldn’t raise your pH that high in a reef tank. Maybe in a tank with nothing but macroalgae. Are you using kalkwasser or sodium hydroxide for Alk? Adding less of whatever is pegging the pH high is what I’d do before adding CO2. After recalibrating
The fact that it drifted up when you changed something doesn’t mean the absolute values are correctly calibrated. If it’s reading 0.2 high at all points that would be important info.
Aeration might help. Normal outdoor CO2 of around 420 ppm results in pH of 8.3 with reef tank parameters. So the more you aerate, the more it will shift towards 8.3 (which is mostly down if your numbers are right). Or lower if your indoor CO2 level is higher than outdoors.
If you aren’t miscalibeated, you must be adding a lot of something that raises pH because photosynthesis alone wouldn’t raise your pH that high in a reef tank. Maybe in a tank with nothing but macroalgae. Are you using kalkwasser or sodium hydroxide for Alk? Adding less of whatever is pegging the pH high is what I’d do before adding CO2. After recalibrating
Hey this is really interesting, I've had issues on my alk dosing - if I dose soda ash, my alk gets too low unless I dose enough to have precip events, and if I dose baking soda my pH drops too low. Where'd you get the idea to mix them, and how is that going for you? How did you come to the 2:1 ratio?
I just mix them according to pH considerations - how high or low the overall pH is and when I dose it. The 2:1 ratio is random, I’ve just been slowly decreasing the soda ash amount as the pH drifts up. I would just dose baking soda if I dosed during the day but since I dose counter to lights on, I don’t want to further decrease the night pH and increase the pH swing by using only baking soda.
More flow where you dose. This shouldn't be an issue as everything should dissolve out when it hits the water.
The pH probe is in a chamber before the return pump chamber, I dose alk and Ca into the return pump chamber, so the additives should have some time to mix in the display before getting back down to where the pH probe is in the sump.
