High Ca & Alk

[melev]

Hi Randy,

Since I just read another thread where you commented that pH 8.0 didn't need limewater, I'm wondering if I should desist and only top off with RO/DI like I've always done.

My latest parameters (http://www.melevsreef.com/parms.html) show such high Alk and Ca that I'm starting to wonder if the limewater is adding to the situation.

My system's volume is 300g (estimate) and I'm using a Ca Reactor to care for those needs. Yes, I'm using Oceanic salt, but water changes are done every 6 weeks and I have to believe that no matter what comes out of the bucket in freshly mixed water will be depleted over time and usage by the reeflings. The tank evaporates about 3g per day.

The effluent is about 1 drip per second into a cup that holds the probe to a pH controller that runs the reactor's CO2 at a setting of pH 6.8 Do you need to know the effluents alk and ca levels? I've never tested those. I only test the tank.

[Randy Holmes-Farley]

I would personally target 8.2 to 8.4, so if you have 8.0, then that range is a fine goal with limewater, although it is not necessary.

but water changes are done every 6 weeks and I have to believe that no matter what comes out of the bucket in freshly mixed water will be depleted over time and usage by the reeflings.

Yes and no. The calcium is high from the Oceanic. Each time the tank inhabitants use some calcium and alkalinity, they are taken down in balance. Each time you use Oceanic, you boost calcium relative to alkalinity. So over time, the calcium rises.

You also have other inputs to the tank, such as the reactor. You could back off a bit on the bubble rate to the reactor, and that will allow alkalinity to fall a bit (and clalcium to fall a very tiny bit). It may also raise pH a bit, although that is not certain.

In general, I don't think that you need to do anything, but if I picked one thing to do, it would be to reduce the CO2 addition rate slightly.

[melev]

Is it the bubble rate in the reactor that I should adjust, or perhaps increase the the pH level that the probe detects? I could switch the pH controller to 7.0 instead of 6.8, for example.

I continue to hate chemistry. ;)

[Randy Holmes-Farley]

You can do either, but I'd decrease t he bubble rate myself.

[melev]

I turned off the bubbles for the next two days to lower alk and ca somewhat. It is still circulating through the reactor.

And you know what, my bubble rate was way way up! It was bubbling out easily 10/second! I don't remember when I did that, but it must have been over a month ago. You see, I get really aggravated to see water going back down the line to the regulator, but for some reason it does that with my reactor. I've added more check valves and it just ignores them. I'm pretty sure I ramped up the bubbles to blow the water back up the line merely to make myself feel better, and forgot about it. :rolleyes: :o

[Randy Holmes-Farley]

Hopefully, that will help, but I'm not sure how to solve the water entering the line problem.

Anyone encounter this situation?

I assume that it is not just gravity? Can you loop the line so that it isn't all downhill?

[melev]

It isn't only gravity driven. I'll have to find a picture of the reactor, but basically there is a venturi tube (for lack of a better word) that hooks up before the intake of the Mag pump that circulates the reactor. That tube goes straight up and into the built-in bubble counter. Under that is a check valve, then the tubing goes down to the CO2 bottle.

I have watched the water go down the line as CO2 forces its way into the plumbing leading into the pump. And when the CO2 shuts off, I've watched the water slowly climb right back up the line toward the bubble counter. I added a check valve in that line to stop the flow, but it didn't make a difference. It still forces its way back through the line into the bubble counter, then back down the line toward the regulator with its own bubble counter.

Since the regulator w/ solenoid has a built in bubble counter I suppose this doesn't matter, but it aggravates me.