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Massive Alkalinity Consumption. Please Help!


wobar

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I have a 40 gallon breeder tank with a mix of coral: sps, lps, and some zoas. None of them are huge colonies. About a dozen pieces in total. Recently, my alkalinity consumption has skyrocketed. Tonight, I dosed up to 9.5 dkh, and within 4 hours it was back down to 8.6, even with my automatic doser adding 22 ml of BRS 2 part within that time. I have increased my daily dosage to 176ml per day, and I still cannot maintain alk.

 

My corals are suffering, and I can't figure out what is consuming all that alkalinity.

 

Magnesium is near 1500, and calcium is holding steady around 420 even with all the dosing.

 

I have more than doubled my dosing within the last 2 weeks, but it seems like no matter how much I dose, within an hour or two, alk drops back down to near 8 dkh.

 

I have no precipitation on my heater or powerheads.

 

Please help!!!

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176ml daily and no change? You are testing wrong or the test kit is expired.

 

Buy a new Salifert kit.

 

Stop the dosing, and do some water changes. 176ml daily is absurd for that sized tank, that's probably what's causing your coral troubles. I'd change 5g daily until problem is fixed.

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I have tested with Salifert, Red Sea, and Hanna, and they are all within 0.3 dkh, so I don't think my tests are wrong.

 

I can test, dose, and test again, and the alk does raise to my target of 9.5. The problem is that within a couple hours it has dropped by at least 1 dkh. My guess is that it is precipitating out somehow instead of staying saturated, but my water is not cloudy, and my heater doesn't have any buildup, so I don't know where it is going.

 

I was already leaning towards a couple big water changes to try to get things back in order. I don't know what else there really is to do.

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righttirefire

Jedi just had a scientific explanation of this. If I remember right it had to do with the nitrogen cycle. Beyond the ammonia/nitrite/nitrate. Something about the sand bed not being mature and not releasing nitrogen gas so it's absorbing the dKH. I do have dKH consumption also but I dose into my ATO water, I'm getting it under control with weekly water changes and adding dosage slowly

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If the sandbed is absorbing it, should I keep dosing massive amounts of alk spread out throughout the day until things balance out? I typically do waterchanges every 1-2 weeks depending on my schedule.

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righttirefire

I recommend you find jedi's post i believe it had a linked article. Maybe pm him... I don't know anything and didn't retain the information. So can't advise

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Admittedly I did not read the whole thread, but here are a few quick points:

 

1) GFO consumes alk when its freshly added to the tank.

2) Coralline, once it takes off, can use a ton

3) 99% of the organisms consume alk/calc/mag in an EXACT ratio. Alk is much less abundant in water then calc or mag so it appears to drop faster then the others. Add to that, hobby tests kits are MUCH more accurate testing alk then calcium. The ratio is "1 dkh consumption is 6.4 ppm calc and 0.71 ppm mag"

4) 8 alk is ideal for most tanks

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righttirefire

 

#390 In Amber Clad: post #390 jedimasterben Posted A week ago

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So the most logical explanation for the significant alkalinity demand when nothing else is dropping is that it is being used aerobically in the nitrogen cycle and that I do not have hardly any denitrification going on to release it back into the system. http://www.reefkeepi...es/2004-12/rhf/

 

 

Randy Holmes-Farley said

Alkalinity Decline in the Nitrogen Cycle

 

One of the best known chemical cycles in aquaria is the nitrogen cycle. In it, ammonia excreted by fish and other organisms is converted into nitrate. This conversion produces acid, H+ (or uses alkalinity depending on how one chooses to look at it), as shown in equation 1:

 

(1) NH3 + 2O2 à NO3- + H+ + H2O

 

 

For each ammonia molecule converted into nitrate, one hydrogen ion (H+) is produced. If nitrate is allowed to accumulate to 50 ppm, the addition of this acid will deplete 0.8 meq/L (2.3 dKH) of alkalinity.

 

However, the news is not all bad. When this nitrate proceeds further along the nitrogen cycle, depleted alkalinity is returned in exactly the amount lost. For example, if the nitrate is allowed to be converted into N2 in a sand bed, one of the products is bicarbonate, as shown in equation 2 (below) for the breakdown of glucose and nitrate under typical anoxic conditions as might happen in a deep sand bed:

 

(2) 4NO3- + 5/6 C6H12O6 (glucose) + 4H2O à 2 N2 + 7H2O + 4HCO3- + CO2

 

In equation 2 we see that exactly one bicarbonate ion is produced for each nitrate ion consumed. Consequently, the alkalinity gain is 0.8 meq/L (2.3 dKH) for every 50 ppm of nitrate consumed.

 

Likewise, equation 3 (below) shows the uptake of nitrate and CO2 into macroalgae to form typical organic molecules:

 

(3) 122 CO2 + 122 H2O + 16 NO3- à C106H260O106N16 + 138 O2 + 16 HCO3-

 

Again, one bicarbonate ion is produced for each nitrate ion consumed.

 

It turns out that as long as the nitrate concentration is stable, regardless of its actual value, there is no ongoing net depletion of alkalinity. Of course, alkalinity was depleted to reach that value, but once it stabilizes, there is no continuing alkalinity depletion because the export processes described above are exactly balancing the depletion from nitrification (the conversion of ammonia to nitrate).

 

There are, however, circumstances where the alkalinity is lost in the conversion of ammonia to nitrate, and is never returned. The most likely scenario to be important in reef aquaria is when nitrate is removed through water changes. In that case, each water change takes out some nitrate, and if the system produces nitrate to get back to some stable level, the alkalinity again becomes depleted.

 

If, for example, nitrate averages 50 ppm at each water change, then over the course of a year with 10 water changes of 20% each, the alkalinity will be depleted by 1.6 meq/L (4.5 dKH) over the course of that entire time period. This process is one of the primary reasons that fish-only aquaria that often export nitrate in water changes need occasional buffer additions to replace that depleted alkalinity.

 

 

So, I need denitrification to happen, not just nitrification and then removal by skimming.

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Just curious but why do you have to maintain a 9.5 dkh?

 

The 9.0-9.5 range is where I have always kept it. I generally hear that 9-11 is a good range.

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The 9.0-9.5 range is where I have always kept it. I generally hear that 9-11 is a good range.

Just wondering. I found that mine settled in at 8.4-8.6 but I guess it all depends on what you have in the tank, your salt mix and dosing.

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What's going on with your ph?

 

Ph is the only test I don't have right now. Going to the store to buy one today. I tried last night, but Petco didn't have any, and the fish store was already closed. I'll post that as soon as I know.

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wobar, do you have a pic of your tank?

 

Something is not right, run the following tests.

 

Salinity with a 35ppt fluid calibrated refractometer

Calcium with a reliable unexpired kit

Mg with a reliable unexpired kit

 

Double check kit instructions t make sure you are doing the tests correctly, the Mg kit is a pain.

 

I like Salifert kits, Red Sea have always been unreliable for me.

 

Double check PO4 and NO3 to make sure you're not experiencing high nutrient levels.

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If I am understanding the long post about the nitrogen cycle correctly, alkalinity would decrease as nitrates increase. As denitrification occurs, alkalinity is released back into the water column.

 

My nitrates test at 0, which would mean 1 of 3 things:

1. My tank is not producing enough nitrates to register on the test.

2. The nitrogen cycle is completing

3. My test kit is bad

 

Assuming the test kit is working, then the nitrogen cycle isn't explaining why the alkalinity is dropping so fast.

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Concentrate on the simple, not the complex IMO. Are you measuring KH at the exact same time every day prior to any dosing?

 

Are you dosing equal parts 2 part when you dose, or just trying to raise Alk?

 

Have you used a reef calculator to determine how much of your Alk supplement is needed to raise KH by the amount you want in the water volume you have?

 

Are you making sure never ro raise KH by more than .5KH during any single day?

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My auto doser comes on 8 times per day. I try to test around the same time per day as much as I can, but life happens sometimes.

 

I am dosing equal parts of BRS 2 part when I dose.

 

I have used a reef calculator, and it is accurate if I dose all at once, i.e. raising from 8.5 to 9 in one go, but I am having trouble keeping it there.

 

For example, let's say I test at noon and it is 8.5, and I dose 2 part to bring it to 9.5, and retest to verify that it is at 9.5. I then increase my doser by the amount I just added. That should hold it steady, but when I retest a few hours later it is back down to somewhere between 8 and 8.5. I have increased my auto doser to the point where it is adding almost 200 ml per day, which is insane compared to what I was dosing a month ago.

 

I never raise it more than 1 dkh at a time if I do a big bump. The doser continues to dose in an attempt to keep it steady throughout the day.

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My auto doser comes on 8 times per day. I try to test around the same time per day as much as I can, but life happens sometimes.

 

I am dosing equal parts of BRS 2 part when I dose.

 

I have used a reef calculator, and it is accurate if I dose all at once, i.e. raising from 8.5 to 9 in one go, but I am having trouble keeping it there.

 

For example, let's say I test at noon and it is 8.5, and I dose 2 part to bring it to 9.5, and retest to verify that it is at 9.5. I then increase my doser by the amount I just added. That should hold it steady, but when I retest a few hours later it is back down to somewhere between 8 and 8.5. I have increased my auto doser to the point where it is adding almost 200 ml per day, which is insane compared to what I was dosing a month ago.

 

I never raise it more than 1 dkh at a time if I do a big bump. The doser continues to dose in an attempt to keep it steady throughout the day.

 

I've given you some advice, you need to answer every question including salinity, all the other tests, kits used, and a picture of your tank. I have to tell you, generally at this poing the reefer crashes their tank because they've made a false assumption and aren't rationally stepping through the tests and each step to diagnose what is going on.

 

I would turn off the doser and stop all dosing, it cannot be used up that fast unless you are dosing both parts at the same time.

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I've given you some advice, you need to answer every question including salinity, all the other tests, kits used, and a picture of your tank. I have to tell you, generally at this poing the reefer crashes their tank because they've made a false assumption and aren't rationally stepping through the tests and each step to diagnose what is going on.

 

I would turn off the doser and stop all dosing, it cannot be used up that fast unless you are dosing both parts at the same time.

I agree

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I just did a 30% water change and turned off my dosers. Here are my current test results:

 

Salinity: 1.025 - refractometer

Alkalinity: 8.5 - salifert

Calcium: 400 - red sea

Magnesium: 1440 - red sea

pH: 7.8 to 8, hard to tell - API

Nitrates: 0 - API

 

picture coming soon

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I just did a 30% water change and turned off my dosers. Here are my current test results:

 

Salinity: 1.025 - refractometer

Alkalinity: 8.5 - salifert

Calcium: 400 - red sea

Magnesium: 1440 - red sea

pH: 7.8 to 8, hard to tell - API

Nitrates: 0 - API

 

picture coming soon

 

Looks good. Stop testing PH, it's not important and the API is inaccurate.

 

Look into getting a Salifert Nitrate test and Phosphate test.

 

Alk of 8.5 is good, you'll be fine all the way down to 6.5.

 

When and how did you calibrate your refractometer? The instructions will say calibrate to 0 with distilled, that is incorrect for saltwater, needs to be calibrated with 35ppt fluid. This is probably not the issue though, just something to keep in mind.

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I've given you some advice, you need to answer every question including salinity, all the other tests, kits used, and a picture of your tank. I have to tell you, generally at this poing the reefer crashes their tank because they've made a false assumption and aren't rationally stepping through the tests and each step to diagnose what is going on.

 

I would turn off the doser and stop all dosing, it cannot be used up that fast unless you are dosing both parts at the same time.

 

I agree with mark there is absolutely no way whatsoever that you are going through that much alk legitimately with 12 corals that aren't massive colonies.

 

Your last set of readings look good, and from what you said you have livestock wise theres no reason you should even have a doser, let alone using one. Water changes will easily get you what your tank needs for now.

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Looks good. Stop testing PH, it's not important and the API is inaccurate.

 

Look into getting a Salifert Nitrate test and Phosphate test.

 

Alk of 8.5 is good, you'll be fine all the way down to 6.5.

 

When and how did you calibrate your refractometer? The instructions will say calibrate to 0 with distilled, that is incorrect for saltwater, needs to be calibrated with 35ppt fluid. This is probably not the issue though, just something to keep in mind.

 

I calibrate the refractometer with 35ppt calibration fluid before mixing water.

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It has been almost 24 hours now. Current test results are:

 

Alk: 7.3

Calcium: 390

 

I am going to manually dose 50ml of BRS alk to bring it up to 8.7, and 150 ml of BRS calcium to bring it to 420.

 

This is much more in line with what I expect the daily drop to be. I'll continue to monitor daily for a while to see if it remains stable.

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