Parameter testing difficulties

[Suohhen]

For the last few weeks I have been testing calcium and alkalinity almost daily in order to try and work out a stable dose but the results have been somewhat erratic. The test kits are all Salifert and the expiration date is 5/21 for the mag and 5/23 for the other two. Here are pictures of the testing results over the period of August 9th until today. The first gap in days was due to me being out of town and during the more recent one I stopped dosing for a week in order to get a better picture of average consumption. I labeled for days which fell after a dosing day, Blue arrows represent element builders, baking soda, calcium +3, and Seachem Reef Advantage Magnesium. The Green Arrows represent 35ml (110 gallon aquarium) doses of Bionic Calc and Alk. The first red arrow on the mag chart was from another person testing. and the other 2 red arrows are pointing to a day where I was pretty sure I put too much water in the calcium vial and too little in the mag. I was using the 5ml syringe to dose 2ml to each and I must have made an error given the results which are corroborated by the fact that it appeared to me that the vials were at noticeably different levels, from that day forward I have been using the 2ml syringe for everything. The results for alk have been relatively clean, but calcium has been all over the place. Do these seem like typical results for the limitations of the test kits or maybe I should investigate further?

 

[Suohhen]

To elaborate on the calcium test, I think a big part of the problem could be the scooper. I have yet to find a way to create consistency with their scoop given the fact that crystals can't exactly be scraped flat so instead I shake the scooper and rescoop as until I have what looks to be a level scooper. I also find the color change to be less clear than the alkalinity kit whereby it is very clear when the color has completely changed with the alk test and not so much with calc.

 

[blasterman]

Saliferts alk test is really good. Even in low resolution mode its pretty good. What I use.

Their calcium test...meh...about as precise as throwing a sock in a closet. Then again its not meant to be. Calcium values are going to be more stable and change at far more constant rates. You aim for the middle of the deviation.

 

[Suohhen]

Their calcium test...meh...about as precise as throwing a sock in a closet.

Haha good one, yeah I have been using them for years and figured as much but I have never done day parameter testing so I never quite experienced it to this degree. I appreciate the confirmation!

 

[rmurken]

I think your red arrows for error in the water level and another person testing are helpful. Exclude those results and your data is somewhat less noisy.

I don’t see anything crazy going on. As @blasterman says, aim for the middle part of the deviation. I’d look at the period from the first point left of the second trough in Alk to the second trough itself as your first clue as to consumption. Dose two-part to that Alk consumption rate and I bet you’re at a decent first approximation for both Ca and Alk. I don’t worry too much re Ca test precision, and only test occasionally to make sure the Ca level is not out of whack with Alk.

Mg depends a bit more on stuff like water changes and your tank’s specific conditions, and it’s slower-moving. Myself, I don’t dose Mg regularly — I just do an occasional test if needed, and a series of doses to keep it within the right range if needed. But that’s rare since I do a weekly water change and don’t have insane bioload.

 

[Suohhen]

Dose two-part to that Alk consumption rate and I bet you’re at a decent first approximation for both Ca and Alk. I don’t worry too much re Ca test precision, and only test occasionally to make sure the Ca level is not out of whack with Alk.

Awesome, thanks for the advice and I definitely agree that alk is always the one to focus on, at least it always has been for me since I never run a heavy amount of stonies. For some reason I all of a sudden got curious and started testing daily, this has certainly been an interesting learning experience.

 

[homer1475]

First and foremost with the deviations, are you testing the same time every day?

And don't get hung up on an exact number, look for trends, and slight devations shouldn't matter. People have found with the trident that tests multiple times a day, that slight deviations are expected throughout the photo period.

 

[Suohhen]

First and foremost with the deviations, are you testing the same time every day?

And don't get hung up on an exact number, look for trends, and slight devations shouldn't matter. People have found with the trident that tests multiple times a day, that slight deviations are expected throughout the photo period.

Dosing happens in the evening after the lights go out or in the morning if I miss a dose. Testing is all over the map and definitely has an impact in the instability of the numbers. I am mostly concerned with the numbers that go down on days after a dose, especially multiple days in a row, but that does seem to be an issue with the precision of the Salifert Calc test which reinforces why it is so common to lean mostly on alk testing.

 

[Randy Holmes-Farley Verified Community Expert]

which reinforces why it is so common to lean mostly on alk testing.

Yes, It's been called the dosing roller coaster in the past, and was the big benefit when balanced methods like a two part became available. Folks can dose calcium based on alkalinity measurement alone, and you will be pretty accurate in dosing calcium if you just match the alk dose. Then, if needed, slowly adjust the dose of calcium up or down over extended periods of monitoring.