Unstable Alkalinity

I have something weird going on...

My relevant parameters are:

Cal 525ppm
Mag 1400ppm
pH 8.3
Temp 80 F

In the last few days, I've noticed my all swinging wildly between 166ppm and 181ppm with no patern present. Today when I watched the all doser dripping alkaline two part (I've stopped dosing calcium to lower my calcium), I saw it forming clouds of flakes instead of cloudy water.

Is this the cause of the instability? If so, what do I do about it?

 

Is it possible that those flakes are settling to the bottom and therefore taking longer to dissolve? Try taking a turkey baster and blow on the bottom of where you are adding it. If they are settling to the bottom, try to have the doser add to a higher flow area. I am currently adjusting my alk.. I have been adding it right in front of the return pump because I have that same flaking thing going on.

 

The alk you are doing is precipitating out as soon as you put it in. Try diluting it out further before you put it in the tank, and dosing it slower (over a longer period). The precipitation is it reacting with the high cal in the water.

 

Also, what are you using to test the mag, cal and alk? Usually I see the alk measurement as dKh.

 

Some of it is probably testing error. However, there could be some precipitation. Calcium carbonate will start to precipitate around a pH of 8.5 or so, if it remains that way for more than a few minutes. Adding an alk supplement, when you are already at 8.3, could definitely get you above 8.5, esspecially if the water isn't mixed very quickly. You could slow down the dosing, add a powerhead to increase the mixing. Increasing the flow through the sump could also help. Also, I dose alk supplement at night and calcium during the day. This can help, as the pH tends to be lower at night.

 

Thanks for the help guys. I've shut off my calcium dosing for a while and it's down to 510. I'm going to drop it to 450; that oceanic salt has so much calcium its actually hard to get to a reasonable level (switched to tropic marin).

I've upped the magnesium slightly, and most importantly, I've directed the return flow across the dosing spot for the alkalinity dosing.

The problem seems to be solved.

 

I have a feeling the problem is your Magnesium level. It should be roughly three times your Calcium level.

 

Yeah, I believe you're right, but I want to bring the calcium down rather than the mag too far up. Even at 510, it is unnecessarily high.