Alk fluctuations - need help understanding

[emilese]

I had been dosing about 1ml a day of the Red Sea liquid alkalinity. This has been keeping my alk stable at 8.4.

The last few days though, my alk has been fluctuating.

Thursday (4/4), alk: 8.1
I dosed Aquavitro Fuel for the first time as I'm trying to boost my nutrients. I adjusted my dose that night to 3ml to compensate.

Friday (4/5), alk: 8.5 - No dosing that night.
Saturday (4/6), alk: 8.0 - Dosed 4ml
Sunday (4/7), alk: 8.6 - No dosing of alk. I did dose Aquavitro Fuel.
Monday (today), alk: 8.5

So, I'm trying to understand why my alk dipped so much on Thursday and Saturday. I thought the increased consumption on Thursday was due to dosing Fuel earlier but, consumption was high on Saturday despite not dosing Fuel. And now the consumption is back to .1 today.

I'm just trying to dial in the correct dosing amount to keep my alk consistent at 8.4.

Any ideas on the fluctuations? Or do I need to just keep monitoring it for another week or two?

Any help is appreciated.

 

[hkgar]

what do you dose Aquavitro Fuel for?

 

[bertoni]

A change of 0.1 units in dKH probably is close to the resolution limit of the test. I'd probably keep the dose fairly constant, and get a longer trend line. I agree that dosing the Fuel might change the consumption rate, so if that dose differs from day to day, you might need to vary the alkalinity dose. I'm not sure how long it'd take from the dosing of the Fuel to the corresponding drop in alkalinity, if any, so that might need some measurement, too.

 

[emilese]

what do you dose Aquavitro Fuel for?

My nitrates are very low and I've been trying to raise it. I've tried increasing my feedings but, they still remain from 0 - 2ppm. I want to make sure my SPS are getting some nutrients.

 

[emilese]

Here's more detail about my system:

It's a 32 gallon mixed reef. Some mushrooms, zoas, a couple lps, but mostly SPS frags.

My latest parameters:
SG: 1.026
Alk: 8.5 (Hanna)
Cal: 425 (Red Sea)
Mg: 1340 (Red Sea)
Nitrate: 0 (Salifert)
Phosphate: 0.19 (Hanna)

Water changes: 4gallons weekly. I did not do one this past week thinking that if I switched to biweekly water changes, maybe my nitrates would climb a little.
Dosing: NoPox daily. Alk as described in the first post. Aquavitro Fuel 7ml - I've only dosed this twice but, I plan to dose 2x weekly. I would love to get Acropower but, it's expensive to ship it here.

 

[emilese]

A change of 0.1 units in dKH probably is close to the resolution limit of the test. I'd probably keep the dose fairly constant, and get a longer trend line. I agree that dosing the Fuel might change the consumption rate, so if that dose differs from day to day, you might need to vary the alkalinity dose. I'm not sure how long it'd take from the dosing of the Fuel to the corresponding drop in alkalinity, if any, so that might need some measurement, too.

Thanks for your input! Yeah, I was wondering if I was wondering if I was fretting over a change of 0.1 too much. I was thinking about getting a doser and I want to make sure I have my dosing dialed in correctly.

The inconsistency of the consumption lately has thrown me off. One day it's 3ml, then the next day nothing. Then 4ml, then nothing.

I agree, a longer trendline is probably necessary. So, you think I should just stick to my normal dosing of 1ml despite the fluctuations?

 

[bertoni]

I would stick to the standard dose until the dKH drops (or rises) 0.5 units or so, and then compute a new dose based on that trend line. You might need to keep working on the dose longer than that, but weekly testing should be fine at some point, rather than measuring every day.

 

[emilese]

I would stick to the standard dose until the dKH drops (or rises) 0.5 units or so, and then compute a new dose based on that trend line. You might need to keep working on the dose longer than that, but weekly testing should be fine at some point, rather than measuring every day.

Thanks for the advice! I think I'm noticing a trend. My alk has been taking a dip when I dose the amino acids (via Aquavitro Fuel). It didn't when I dosed amino acids on Sunday but, last Thursday and today when I dosed, both times it dropped by .3 - .5ml

This is just a theory but, because my nutrients are low, my SPS are probably starved so, when I add the amino acids, they start to consume alkalinity. I will continue to monitor and continue to try and bring up my nitrates.

Another question, should I stop dosing NoPox while I'm trying to bring my nitrates up? I also removed my filter floss this week to seed a QT tank and to try and "dirty up" the tank. Should I also continue to run without filter floss?

 

[hkgar]

How many fish do you have? The more fish the happier your SPS will be, because more food equals more nutrients in the water for the corals.

 

[bertoni]

I agree that it's possible that the corals need more food. Taking out the filter sock is reasonable, and I'd stop the NOPOx, or at least cut back gradually. Keeping an eye on the nutrient levels and the corals is very important while you are making such changes, though.

 

[dkeller_nc]

I'd echo stopping the NOPOx - this is carbon dosing of course, and one of the aims of carbon dosing is increasing the bacteria in the system that are consuming nitrate and phosphate as they grow. Since you're trying to increase nitrate, dosing NOPOx is working against you.

 

[emilese]

How many fish do you have? The more fish the happier your SPS will be, because more food equals more nutrients in the water for the corals.

I now have 4 small fish: 1 pink streaked wrasse, 1 rainford goby, 1 ruby red dragonet, 1 McCoskers flasher wrasse.

I just added the flasher wrasse and I'm already thinking that I will not keep him long term as I feel he will do best in a larger tank. Some will say my tank is too small for the ruby red dragonet but, the tank is well established (1.5 yrs), I supply a fresh batch of copepods regularly (there is a supplier that I buy from and they have reasonable prices). I also feed him baby brine shrimp daily.

 

[emilese]

I'd echo stopping the NOPOx - this is carbon dosing of course, and one of the aims of carbon dosing is increasing the bacteria in the system that are consuming nitrate and phosphate as they grow. Since you're trying to increase nitrate, dosing NOPOx is working against you.

Thanks for the advice! Yeah, I'm noticing that the NoPox seems to be more effective with nitrates than phosphates. I'm going to see how stopping the NoPox dosing affects my system.

 

[dkeller_nc]

By the way, while I'm doubting the Fuel would have enough organics in it to actually cause this, it is true that the breakdown of food to ammonia and then to nitrate consumes carbonate, which obviously factors into alkalinity in a seawater system. In theory you get the alkalinity back if bacteria in your system reduce the nitrate to nitrogen gas, but it's not uncommon in reef tanks for there to be little of this nitrate reduction. That shows up in an imbalance of alkalinity to calcium consumption, since some of the alkalinity is going towards oxidation of ammonia to nitrate.

 

[emilese]

I'm still struggling to get a handle on my Alk readings. The latest is that my Alk is climbing higher without me dosing anything.

It went from 9.3 on Sunday to 9.7 today. I have not dosed anything except some Acropower.

Why would my Alk climb? Do you think that I may have a faulty Hanna checker?

 

[reefgeezer]

The Hanna tester is pretty accurate...Less than +/- 0.1 when reading 8-9 dKh. That rating is just for the hardware. It doesn't take into account measurement variability created by the testing process. It's not that you are doing anything wrong. It just means there are variables in every testing process that impact the accuracy of individual tests. Things like cleanliness and clarity of the vial, cloudiness of the water, slight variance in water volume in the vial, small variances in the reagent, and etc. can change the reading a few tenths.

You have to get away from comparing individual tests. Start a spreadsheet and record each test. Then analyze the trend rather than the delta between individual tests. Good decisions are usually based on the longer trends.

 

[emilese]

Thanks John for your reply. I have been keeping a record of my tests and I've gathered a long trend now.

The current question I have now is why would my alk increase when I haven't dosed anything? What could cause alk to rise?

 

[bertoni]

I suspect that the issue is testing limitations of some sort. I'd keep measuring for a few days to see what happens.