CARX tweaking? (high alkalinity)

[Isaac]

Last couple weeks, I;ve noticed my alkalinity rising, while my calcium and magnesium drop at a normal ratio.

 

water readings:

	dkh	ca	mg
tank	13.5	440	1260
effluent	20	500	1260

As you can see, my effluent is dkh heavy, compared to other readings (and mg is low, ugh). effluent flow rate is about 0.06-0.10 l/m (blame Dan for selling me a flow meter!)

"what changed?" I got the flow meter, i had to increase output, which in turn i increased co2 to match. I use A.R.M. Coarse with some pretty old "ultramag" mixed in. ph in the CARX stays between 6.5 and 6.6:


so... why is my alkalinity at a much higher ratio of what it should be, compared to the calcium? (I know why the mg is low)

I've been having to add calcium and magnesium in my waterchange water to help lower the dkh at this point. Anyone else seen this before? recommend a different media?

[jolt]

I have to ask, but knowing you Isaac I think I already know the answer. Is your Ph probe calibrated? Seems like you are dissolving media faster than you think. So if the Ph was actually lower than you think then more media is dissolving and with the increased effluent rate this is causing Alk to be high, and the calcium is precipitating because your mag is low. Could that explain your situation?

[Gig 'em @ NDstructible]

This may be a dumb question, but how old is your calcium test kit? I find it odd that calcium would be splitting off away from alk that quickly. Could it be that your calcium test kit has expired? Have you tried comparing your test results to that of another test kit? I struggle with lower Mg in my tank top and added NeoMag to the reactor. I didn't see Mg rise until I lowered the pH in my reactor below 6.5. It seems to not dissolve very well in closer to neutral water and requires a more acidic environment. This is just my observation in my own reactor, so who knows if it's the same for you. Like Jolt said, I would also check your pH probe and recalibrate it.

[Sascha D.]

SG below 1.026 could cause difficulty maintaining balance.

[Isaac]

@jolt: calibrated 2 months ago. replaced half the media 2 months ago as well

@gigem: api expires 2017, redsea 2018, used both.

@sascha: temp 78.1-78.3 salinity 34.9-35.1 ppm (so thats about 1.02475 compensating for temp) 1.026 @78 is 36.7 which seems insane *lol*

[Sascha D.]

I guess I should have said salinity below 35 ppt!

As I understand it, every 2.8 dKH adds 20 ppm Ca. If you were at 11 dKH and 420 Ca, then the addition of 2.5 dKH would add about 18 ppm Ca. The API test kit reads in increments of 10, so 440 ppm seems inline to me. What has your usage been trending?

[Isaac]

my dkh was 8.5-9 before I upped the effluent volume. I think if the effluent was 14-16, not 20.. it wouldn't be so... off. w/ the api kits, you can guess "half" or "midway" readings once the color starts turning (about half way.. color wheel wise), and the next drop completely turns... thats a half-ish. (redsea is more accurate, very hard to see a "half" color)

I need to get more hanah regents I guess. I'll test again in a bit w/ all three (well, if i have the regents for the 3rd anyways)

[Dan H]

I just sold it, I didn't require you to actually use it.

For the Mg, you can always add some neomag to the reactor. I have to run about 8:1 ARM : NeoMag to keep my Mg around 1400-1500. I have no idea why the calcium would be off.

[Isaac]

Well... yyeeeaaaa...

	dkh tank	dkh CARX	ca tank	ca CARX
API	14	20-20.5	440	480
Red Sea	13.85	19.3	440	490
Hanna	11.6 (207ppm)	15.7 (280ppm)	no regent	no regent

I'm actually impressed at how accurate the API calcium one was... Altho since you need 20+ drops, it makes sense (smaller fractions w/ more drops)
Cant say I trust the hanna regent. its an unexpired, opened last month bottle... which is... weird. Is everything else wrong? the most precise one is the outlier.. strange.

[victoly]

Like others, I think the most likely scenario is measurement error in alk/pH/Ca/Mg. There aren't a whole lot of common scenarios in an average tank (with the assumption that this is a SPS-dominated, growth heavy tank) that cause alk and ca to come out of balance with a CaRx.

[Isaac]

Anyone else use ARM Coarse? what pH you running it at?

side note... all the softies are huuuuge.. so its not really impacting the tank, just worried its on its way to impacting the tank w/ these readings.

[Dan H]

I'm using ARM coarse and neomag. My flow is 130mL/h and pH is kept between 6.3 and 6.7.

[Isaac]

whoa, that a high flow. whats yer co2 set to... in bubble counter terms "god knows it goes too fast?"

if i double my flow, itg would just make my alk rate raise higher compared to calc. I'm thinking the media is at fault?

[Isaac]

I added a whole other chamber w/ ARM and more mag on the effluent end, increased the flow, upped the co2... ill check it in a few hrs

[Dan H]

I have my carbon doser at 2 second and 15psi.