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uskram
05/30/2014, 08:43 PM
I have been dosing Soda Ash and Calcium Chloride from large reserves mixed a long while ago and finally have my dosing matching the tank uptake. Now that everything is settled in I am running out of prepared supplements and am not sure of the concentration I mixed up previously. To avoid the lengthy process of reestablishing dosing times I would like to determine the concentration of the supplements I haves been using. I know the concentrations are not according to Randy's Recipe. Would anyone be able to offer some guidelines to use standard dkh and CA test kits with dilutions to determine the concentrations of supplements?

disc1
05/30/2014, 09:15 PM
How concentrated do you think they are? Gimme a range to work with.

The math is simple, multiply the result you get by the dilution factor. If you cut it 1:100 (1 part supplement to 99 parts DI water) and you get 370ppm, then the solution is 37000ppm. Just multiply by 100. Pick a dilution ratio that puts you in the range of the test.

All that is for naught if you don't have a good way to measure the volumes. If you're measuring the dilutions with syringes or something then you're only as good as the error on the syringe and that ain't great. But will at least get you close.

uskram
05/30/2014, 10:11 PM
I think they are approximately 1/2 of Randy's Recipe. Short of a graduated cylinder, which I don't have, what would you suggest as the next best approach for volume measurements?

disc1
05/30/2014, 10:33 PM
I'm guessing a syringe is probably your best bet if you can't get any volumetric glassware. Just remember to take the result you get and think of it as a ballpark number.

The important thing is that you pay attention to how you make it this time so once you get the dosage on this batch figured out you will be able to repeat it. Consider this a lesson in "Taking Notes: 101" at the good old School Of Hard Knocks.

uskram
05/31/2014, 08:45 AM
I managed to get a graduated cylinder. One step in the right direction.

Just to confirm I have understood things correctly:

If I suspect my CA supplement is 18,500 ppm I should add 1 ml of supplement to 49 ml of RODI water and test with my Red Sea Pro Calcium test kit and multiply the result by the total volume of the sample, 50, to determine the supplement concentration. If correct, Test result should be close to 370.

If I suspect my dKH supplement is 2660 dKH I should add 1 ml of supplement to 249 ml of RODI water and test with my Red Sea Pro or Hanna Alkalinity test and multiply the results by the volume of the sample, 250, to determine the supplement concentration. If correct, Test result should be close to 10.64.

Thanks again for your help. In rereading Randy's 2 part article, http://reefkeeping.com/issues/2006-02/rhf/index.php#19, I realized I probably didn't recognize the fact that Recipe 1 and Recipe 2 were producing different supplement concentrations. When I ran out of BRS 2 part mix and went the DIY approach I just mixed things up according to what I assumed to be the new and improved Recipe 2 ,not realizing there was a difference. This is likely the reason my dosing went out of whack and it took so long to restore. This exercise has proven very educational.

Randy Holmes-Farley
05/31/2014, 10:29 AM
If I suspect my CA supplement is 18,500 ppm I should add 1 ml of supplement to 49 ml of RODI water and test with my Red Sea Pro Calcium test kit and multiply the result by the total volume of the sample, 50, to determine the supplement concentration. If correct, Test result should be close to 370.

Yes, that is correct, and so is the alk test.

Good luck. :)