AC3 controlling ALK dosing

[qfrisco]

Hi all -

I just hooked a couple Drew's Dosers to my AC3 to automate dosing of my 2-part.

I want to add the ALK part very slowly over a span of several hours. Below is how I'm doing it - dose for 15 minutes every hour, starting at 30 minutes past midnight.

If Time > 00:00 Then ALK OFF
If Time > 00:30 Then ALK ON
If Time > 00:45 Then ALK OFF
If Time > 01:30 Then ALK ON
If Time > 01:45 Then ALK OFF
If Time > 02:30 Then ALK ON
If Time > 02:45 Then ALK OFF
If Time > 03:30 Then ALK ON
If Time > 03:45 Then ALK OFF

It appears to be working fine, but it bothers me how unsophisticated the program is. :-) Is there a more elegant way to do this? I'm thinking I could use the OSC command, but how can I get it to start only at a certain time?

[clp]

You can use another timer name to keep it from dosing. Like

OSC 015/060 ON/OFF Then ALK ON
If Timer LT1 = ON Then ALK OFF

Where LT1 is a light timer or another timer which is on during the day and off at night.

Curt

[dcmartinpc]

I would add a statement that shuts off the ALK if the PH is higher than say 8.3....

Just a thought.

Don

[qfrisco]

Very cool - thanks, Curt, for that suggestion. I'll work that into my program.

Don - thanks to you too, for the PH failsafe. Can never have enough of those.

[ciphros]

I have the drew's barebones dosers. I dose only at night with a 7ml/min rate. Here's my code with the pH stop code (I stir constantly with a maxijet in empty IO salt buckets - stir starts 5 min. before I start dosing, and if for some reason it's shut off manually, it won't dose):

If Time > 00:15 Then AKS ON
If Time > 00:51 Then AKS OFF
If Time > 00:25 Then AKD ON
If Time > 00:50 Then AKD OFF
If Time > 04:50 Then AKS ON
If Time > 05:26 Then AKS OFF
If Time > 05:00 Then AKD ON
If Time > 05:25 Then AKD OFF
If pH > 08.40 Then AKD OFF
If Timer AKS = OFF Then AKD OFF

I keep my tank at about 3.0 to 3.5 meq/L (270 gal tank) with this dosing rate.

You can see my pH graph here:

http://www.rowelab.com/AquaController/index.php?userid=nate+c.&scope=7days

The sharper peaks are the dosings, and the broad humps are the natural increase during the photoperiod for the day.

I've been toying with the idea of decreasing the dose rate (I've got the older DC motor dosers that I can vary voltage on to slow them down further) to try to keep the night dosing on longer, but dose the same amount and try to minimze the pH change through the entire night.