2-Part dosing question

[Brew12]

As a new reefer I hadn't been planning on dosing anything for awhile. I have almost no coraline growth and had 20 small frags in my tank. 10 sps, a few zoas and small variety of lps/soft corals.

I had only been testing my calc weekly but it dropped from 430ppm down to 380ppm in a week. My Alk has been fairly stable in the 8-9 range. Since I had an Apex DOS that came with the system, I ordered BRS 2-part when it was on sale so I just happened to have it available.

I went to an online calculator to see how much calc I should add, and measured out 1/4 of the recommended amount. I thought I had read somewhere that you should add equal parts of each 2-part because of a relationship between calc and alk.

Needless to say, this caused a massive alk spike, one sps frag was bleached the next morning, another bleached the day after. A third sps frag started to bleach but looks to have stabilized.

I still haven't set up the DOS yet (maybe this weekend) but here is my question. Should I be trying to dos both of the 2-parts in equal amounts or should I be testing for each separately and dosing each as required by their individual measurements?

 

[ksfulk]

Should I be trying to dos both of the 2-parts in equal amounts or should I be testing for each separately and dosing each as required by their individual measurements?

You should be measuring each and dosing as required. (I dose 9.2mL of Alk daily and 0.2mL calcium)

Upon startup of 2 part dosing, until you reach tank equillibrium, you'll note that the elements can go wonky (to use a technical term) for a while. Outside influences can also skew your results (salt mix in water changes, evaporation, precipitations, livestock makeup, presence of phosphate, etc). My suggestion would be to monitor each parameter daily for a week (without dosing) to determine what your daily consumption of ALK & Calcium is - then you can set up your dosages based on this information. I would continue to monitor daily until your parameters are stable, then you can reduce testing as needed.

Something to note, be sure that you monitor the parameters daily for a while and dont react immediately to the numbers - realize there is some variability in the testing as well. I monitor ALK daily (easy with a Hanna checker) and Calcium every other day or so, even though my tank is only 2 months old. Testing at the same time each day is important to remove additional variables from your data set.

 

[Brew12]

I've had another person mention that they thought the 2-part should be added at a 1:1 ratio. Is this just a common misconception? Any other opinions on this?

 

[ksfulk]

I've had another person mention that they thought the 2-part should be added at a 1:1 ratio. Is this just a common misconception? Any other opinions on this?

It depends on the 2 part in question and the system you are using. Triton, for example, you dose all parts equally - but the inherent differences that Ive noticed is that with stand alone "2 part" (like BRS, ESV, etc) you are setting the parameters, inputs and outputs (ie you decide the salinity, alk value, calc value, etc), where as "2 part" that is designed to settle at their specific values (for Triton its 8dKH, cant recall the calc value off the top of my head), so you dose all parts in equal to get their values.

For what its worth, Ive only every dosed Triton 2 part in equal values. Ive used BRS 2 part for several years and it was always different amounts, and same with the ESV 2 part Im currently using. Just because something comes together, doesnt mean the values are tied to one another - however, many 2 part additives have similar dosing regimients (X ml/100 gallons Part 1, X ml/100 gallons Part 2) coupled with instructions of dosing both parts (1 and 2) that add to the confusion.

 

[Knapp870]

I agree with ksfulk. I started dosing 2 part a year or so ago and I dose each piece independent of one another based on my tanks needs. Set your goal alk/calc levels and dose to those levels. I use kalk in my top off to dose both in a 1:1 ratio but adjust each independently via 2-part

 

[cb684]

I agree that the 2 part dosing is intended to allow dosing for individual needs of carbonate (or bicarbonate) and calcium. With that said, it has been over one year that I only test for alkalinity and dose the same volume of carbonate and calcium using the BRS solutions. Corals are growing well in all my systems (now I have 3 systems two 300 gallon systems and one 40 gallon. I do want to highlight that I keep a relatively low alkalinity (6.5 - 7.0).

 

[Randy Holmes-Farley]

I've had another person mention that they thought the 2-part should be added at a 1:1 ratio. Is this just a common misconception? Any other opinions on this?

It should be. It is designed that way (or should be), and will closely balance the needs of an aquarium, but water changes often mess with the demand ratio. The in-tank things that mess with the ratio are minor, but increasing or decreasing nitrate can impact it.

IMO, most folks could dose exactly 1:1 for a very long time to maintain alk, and won't have a problem with calcium getting too high or too low.

 

[Brew12]

It really was a bad move on my part, and I appreciate all of the feedback. I think I have a better understanding of it now. The 1:1 dosing would probably have worked if I had added both slowly using dosing pumps and had my tank chemistry been where I wanted it. Trying to raise my calcium using larger batch adds, and matching the alk to those batch adds, is where I went wrong. Regardless, matching it 1:1 isn't necessary and I probably won't do it in the future. I will set both pumps individually.

I can't even say the 1:1 is bad advice. I just didn't understand it well enough and applied it to the wrong situation.