Why do I keep having to do correction doses while using 2 Part?

Phyber · Feb 5, 2020

Hi! I run BRS 2 Part on my 65g reef. My goal is to hold alk somewhere around 8.3-9 dkh. I use Neptune DOS for Alk and Cal, and monthly I calibrate the pump heads. The worst that either of them have been off is pumping 39.0ml vs. the intended 40.0. I can press the manual dose button and fluid will flow no problem.

I test my alk twice a week (usually Wednesday and Saturday) with a Salifert kit. the first few times this happened I ordered a fresh Salifert alk kit, but even with that my numbers are matching.

Last Saturday (Feb 1) I tested Alk at 8.3. Today (Wednesday Feb 5) I test at 7.4 dkh. The BRS calculator calls for 41ml of a correction alk dose (liquid pharma soda ash) to get me back at 8.3. I'm dosing 20ml tonight, 20ml tomorrow.

My question is: Is it normal to do these correction doses? The last time this happened was on January 22 (not that long ago). If I'm assuming correctly, I'm supposed to take my BRS calculator readout for a correction dose of 41ml, divide that by 4 (the number of days between tests where I saw a fall) and that's the daily amount I'm supposed to be dosing, correct? If that's the case the calculator says I should dose 10ml, and I'm already dosing 12ml.

ckalupa · Feb 5, 2020

Is the doser holding the level product in the hose when stopped or a possible seal issue allowing the alk to flow back in the hose back into the feed supply from the doser? If the later is the case it is possible it is under dosing. Air bubbles in the line?

Phyber · Feb 5, 2020

ckalupa said:
Is the doser holding the level product in the hose when stopped or a possible seal issue allowing it to flow back on the hose from the feed supply to the doser? If the later is the case it is possible it is under dosing. Air bubbles in the line?

I have the DOS mounted higher than the containers and I use RODI tubing to connect everything. No "backflow" when pump is running, it stays right at the tip of the outlet tube.

There is an occasional air bubble that forms at the top of the output tube (right outside the outlet of the head), but even when I leave it int he tube and do my calibration run I still get very close to 40ml and it doesnt stop flow.

ckalupa · Feb 5, 2020

When the pump stops does the product drain back into the bottle from the doser connection back?

ckalupa · Feb 5, 2020

The doser will register as adding product even if it is pumping some air.

Phyber · Feb 5, 2020

ckalupa said:
When the pump stops does the product drain back into the bottle from the doser connection back?

No, fluid is held in the container side tubing as well. A "vaccuum" on both sides.

Phyber · Feb 5, 2020

ckalupa said:
The doser will register as adding product even if it is pumping some air.

Even with the bubble, the calibration method still pumps very close to 40ml in the measuring beaker.

ckalupa · Feb 5, 2020

Might also have some precipitation happening. The calculators get you close but there can be some batch variance on the alk product too. 12 over 10 sounds like 20% more but is not significantly more imo. Does 12 hold your desired level or that too falls short?

Phyber · Feb 5, 2020

ckalupa said:
Might also have some precipitation happening. The calculators get you close but there can be some batch variance on the alk product too. 12 over 10 sounds like 20% more but is not significantly more imo. Does 12 hold your desired level or that too falls short?

12 held for a bit. I guess I can attribute it to coral growth, just thought I'd see a slower rise in uptake. Seems to be a spike every few weeks or so

Cory · Feb 6, 2020

Have you adjusted water flow? I find changing water flow changes my alk uptake.

Randy Holmes-Farley · Feb 8, 2020

I’m not sure I understand the issue. You should set the daily dose to maintain alk iteratively. Demand drops as alk drops so a multi day alk drop test will always underestimate demand.

Phyber · Feb 8, 2020

Randy Holmes-Farley said:
I’m not sure I understand the issue. You should set the daily dose to maintain alk iteratively. Demand drops as alk drops so a multi day alk drop test will always underestimate demand.

Alk continues to drop despite dosing equipment being verified working correctly. I understand coral uptake spikes will deplete my all level if not fully dosed for, but I'm having to do correction doses on top of daily doses almost weekly.

Just wondering if everyone has to do correction doses a d how often?

Cory · Feb 8, 2020

I would say its normal. But are you using a doser or by hand? Id also try just regular baking soda (sodium bicarbonate).

Phyber · Feb 9, 2020

Cory said:
I would say its normal. But are you using a doser or by hand? Id also try just regular baking soda (sodium bicarbonate).

Neptune dos!

madweazl · Feb 9, 2020

No, weekly corrective dosing isn't normal. How much do you trust your abilities to perform the alkalinity test and how much do you trust the test kit? If I had to guess, I'd tend to believe you and your test kit are the issue.

With that said, I will get spikes in growth that consume considerably more alkalinity on occasion but I can usually attribute that to something changing within the tank as well (changes to lighting for instance).

Phyber · Feb 9, 2020

madweazl said:
No, weekly corrective dosing isn't normal. How much do you trust your abilities to perform the alkalinity test and how much do you trust the test kit? If I had to guess, I'd tend to believe you and your test kit are the issue.

With that said, I will get spikes in growth that consume considerably more alkalinity on occasion but I can usually attribute that to something changing within the tank as well (changes to lighting for instance).

I'm pretty stable in performing these Salifert tests and I can easily see the color change. If this was a small change (say 8.6 to 8.3) I could attribute it to test quality tolerance, but this is about 1 dkh worth of difference.

I haven't change anything in the tank in months. Maybe it's just my clam taking up more...or my frags getting a growth spurt.

Bryknicks · Feb 9, 2020

It shouldn’t be jumping around that often u less Something in the system changed. Was it ever holding an all number you were comfortable with or have you always had this problem? Does your calc hold steady or are you chasing numbers there as well?

fragit · Feb 9, 2020

If I am understanding this situation correctly I don’t believe your correcting at all. For instance (arbitrary numbers). If your DKH is 8.3 and you dose 10mL/day and want to increase to 9.0 DKH and a calc tells you to dose 5mL to reach 9.0dkh you should dose a total of 15mL. Splitting your corrective dose over 4 days is not gonna work, your always chasing your tail. Now we know sometimes you can’t just dump a bunch of Alk solution without a huge swing. But your using a doser so In my opinion divide your corrective dose (15mL in my example) over the number of time you dose in 24hours that is your new dosing amount/event. Recheck DKH in 24 hours and adjust. Always make small increases. My point is it doesn’t sound to me like your changing your daily dosing amount, just adding a corrective amount. This is not going to change your DKH long term as the alk is being consumed.

madweazl · Feb 9, 2020

Phyber said:
I'm pretty stable in performing these Salifert tests and I can easily see the color change. If this was a small change (say 8.6 to 8.3) I could attribute it to test quality tolerance, but this is about 1 dkh worth of difference.

I haven't change anything in the tank in months. Maybe it's just my clam taking up more...or my frags getting a growth spurt.

With results of less than 1 dKh, you're asking a lot from this test kit (I wouldn't expect to get much closer than .3-.5 dKh with any consistency).

Phyber · Feb 9, 2020

fragit said:
If I am understanding this situation correctly I don’t believe your correcting at all. For instance (arbitrary numbers). If your DKH is 8.3 and you dose 10mL/day and want to increase to 9.0 DKH and a calc tells you to dose 5mL to reach 9.0dkh you should dose a total of 15mL. Splitting your corrective dose over 4 days is not gonna work, your always chasing your tail. Now we know sometimes you can’t just dump a bunch of Alk solution without a huge swing. But your using a doser so In my opinion divide your corrective dose (15mL in my example) over the number of time you dose in 24hours that is your new dosing amount/event. Recheck DKH in 24 hours and adjust. Always make small increases. My point is it doesn’t sound to me like your changing your daily dosing amount, just adding a corrective amount. This is not going to change your DKH long term as the alk is being consumed.

I dose over a 24 hour period for both parts so at any given time I should be holding a steady reading. It's not a once a day dose.

Some weeks I can hold an all reading without adjusting dose amount. Then the next week I get readings of dropping all big-time over a 4 day period. I'll up my dose amount and then be back to square one.

I want to be 8.6 ish to give me wiggle room for things to happen. When I dropped to 7.4 the BRS calculator said it would be 41ml to correct...why shouldn't I divide that by the days of when the drop happened (4 days, Saturday to Wednesday)? The dos currently runs every 15 minutes so how am I supposed to adjust for every dose period??