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ScottB
10/17/2011, 10:47 AM
Ok, what I want to do is this: At night when my pH drops below my threshold I want to dose 2-part. Simple enough with the code in the UUG, right:
[Calcium]
Fallback OFF OSC 000:00/003:20/057:40 Then ON
If Outlet [Lights] = ON Then OFF
If pH >8.35 Then OFF
If FeedA 000 Then OFF

[Alkalinity]
Fallback OFF
OSC 030:00/003:20/027:40
Then ON If Outlet [Lights] = ON Then OFF
If pH >8.35 Then OFF
If FeedA 000 Then OFF

However, if I understand it correctly, 2-part should always be dosed in balance. Therefore, I would assume that the above code could lead to unequal dosing. For example, if the dosing of the calcium raised pH above the threshold, the next pass of Alk would be skipped if pH failed to drop. This could continue theoretically forever, with Alk never getting dosed.

So, is there a way to ensure that if pH falls below a certain threshold that both Calc and Alk get dosed 1 each a half hour apart? Or am I over thinking this?

Raoul5Duke
10/17/2011, 10:54 AM
I would suggest dosing based on your corals uptake needs, not in an effort to stabilize your PH otherwise you will get big swings in CA & Alk which will have neg. effects on you tank inhabitants.

I believe equal parts over time is fine. For example my alk dosing pump works from 11 pm to 11 am to keep Ph up @ night while my Ca works 11 am to 11 pm. Over 24 hours they are dosed in balance, but again its a balanced range not specifically if Ca is "x" Alk has to be "y". In short I think you are making it overly complicated. I hope that helps some.

swearint
10/17/2011, 11:08 AM
You are overthinking it a bit. The exact dosing schedule/strategy will depend on the particular supplements used and the particular demand. Not all two-part supplements will even effect the pH. And the dosing may not even be 1:1 Ca/Alk. I use baked Baking Soda for Alk supplement and it does raise pH. I have it scheduled to start several hours after lights go out and the pH has dropped about half way to the lowest point (the Apex graphs help with this). Then I dose over an extended period such that the pH flattens out until the desired dosage is complete and begins to fall again until the lights come back on. In otherwords, the pH check is just a failsafe measure.

Todd

ScottB
10/17/2011, 12:21 PM
Thanks folks. I will step back a little and take the K.I.S.S method.

ciphros
10/17/2011, 05:52 PM
Also, it's the Alk portion that will raise pH, NOT the Calcium.