GHL Doser Issue

Brad Bessett · May 23, 2018

Hello all, not really an emergency but I brought my GHL Doser online on Saturday from alk dosing in my ATO and calcium by hand.

Did my calculations and the 2 part dosing has been rock solid ever since.

Testing twice daily and ALK has always been 8.6 or 8.7. Dosing 36 one ML doses daily in my 145 Equal parts.

Calcium has been holding at 420-430 and the last few nights I've dosed by hand in an attempt to get it to 450 and then let the Doser maintain.

Come home tonight and the alk is 8.3.

Odd.

Test Calcium and it's over 500.

That causes alarm.

Any thoughts? The hand dosing I've been doing has been for multiple nights so I want to rule that out.

Salifert tests, tested 2x each tonight.

scuzy · May 23, 2018

Have you calibrated each doser head?

Brad Bessett · May 23, 2018

Yes, was very precise in setting up and calibration. Doser has been flawless up until tonight's tests.

Did not test this morning.

scuzy · May 23, 2018

Well one possibility is your corals are growing consuming more alk?

Brad Bessett · May 23, 2018

I've been expecting that, and knew I'd soon need to tweak the Doser settings.

But 420 calcium to 520 in 24 hours?

scuzy · May 23, 2018

What kind of corals do you have?

scuzy · May 23, 2018

Btw what was the size of tank and readings before doser?

Brad Bessett · May 23, 2018

90 display, 20 ish gallon sump, 27 gallon frag tank plumbed in.

SPS dominant mixed reef. And Ilby dominant I mean highly dominant.

Brad Bessett · May 24, 2018

The readings were 8.7 and 430 before the Doser went online.

Maritimer · May 25, 2018

I know that sometimes when corals stress for whatever reason, their uptake can drop off ... #reefsquad, any thoughts on why Brad's calcium and Alkalinity would make a sudden jump? (Gorgeous corals, by the way!)

~Bruce

Brew12 · May 25, 2018

So Alk dropped but Calc climbed?

It does sound like a doser issue. I would recalibrate them again. Also make sure you don't have a situation where the calc is siphon draining into the tank and adding more than expected.

What is your Mag?

ihavecrabs · May 25, 2018

Definitely sounds like a calcium overdose. That explains both the significant rise in calcium but also the drop in alkalinity.

"If, for example, you add too much of a calcium supplement, you will drive down alkalinity as you get precipitation of calcium carbonate in the tank."
Source: https://www.advancedaquarist.com/2002/11/chemistry

And that is one seriously awesome picture. You have some beautiful coral my friend.

reeferfoxx · May 25, 2018

@Brad Bessett Does your dosing containers have measurements? Does it let you see the remaining fluid ounce in mL? Meaning, when you are in the application, after calibration(or before), you set the level amount of solution to the appropriate number(ie 1000mL). Curious if the numbers are similar. I wouldn't put much faith in the containers measurements vs weight but.. should be close. If it's to late, after re-calibration, letting the doser run a series of doses and then compared the remaining fluid to the applications remaining number?

Little back story with my 2.1. I had calibration issues at the start. Come to find out the "scientific graduated cylinder" from Amazon was no good. GHL recommended I calibrate using scales that can measure down to 1/10th a gram. As 1 gram = 1 mL. This worked out perfectly for me.

Brad Bessett · May 25, 2018

Thanks all for the input. I'm chalking this up to me overshooting the CA dose by hand the two nights I did it. The other day I bumped up the Alk amount by a few ML and it's on its way back up. As of last night it was to 8.5 and still climbing. I cut the CA down by 25% and may cut it even more if I can't get it below 500.

These were my first adjustments since going live with the reactor and I figured it was too good to be true. I was expecting to have to make adjustments, what threw me off was the 3 days of steady params before the blowout (which I do think was by my hand).