Alkalinity - Ca imbalance - why?

[Anonymous]

Gee i hope this is not too confusing.

I have harvested lotsa macros but not as much now that nitrates got down to 0.0.

Some macros do have a large CA appetite. perhaps I should try some of those?

Yes I do run FW planted and have for years. no dosing there either.

thanks for your observations. Again this is where my system has stabilized. Being as my fish and corals look fine I'll just let it be.


Bob

 

[Mouse]

I was hit by a bit of a eureka moment last night, (bear with me this could be painfull). And anyway, i was thinking. You seem to have a very high Ca level, 400-450 is within the realms of a very well supplied system. I've heard of people with Kalkwasser Reactors and Calcium Reactors running in tandem, and only just manageing the same sort of level. And allthough ive heard very good things about b-ionic, i find it a little difficult to beleave that that alone could be responsible for the levels you have.

You also say that your system expiriences huge PH drops at lights out, diminished Kh levels that are disproportional to the Ca usage of a regular balanced reef. (allthough i feel this 'balance' is meerly coincidental)

Anywho, it seems that the large ammount of macros in the system are responsible for this imbalance. So that would also indicate that they are growing very well.

The large Ph drop at lights out must be due to the plants respiration, as im sure your well aware, plants photosynthasise by day, and respire at night, taking in Oxygen and releasing C02.

Reef tanks, being heavily skimmed, will have an abundance of oxygen in the water, and very little C02 due to the aggitation and resulting dissipation by the skimmers air/water mix.

This would be a bad situation for the plants during the day, but near on perfect conditions for nightly respiriation.

What im thinking is that the C02 relased by the plants during the night, due to the optimal conditions for respiration, is causing elevated levels of Ca to be released from the sand bed. Its as if your Ph drop assisted by the Co2 in releasing the Ca, a bit like super charging Kalkwasser with vinegar.

Potentially, this could be another method of creating a natural system, with a semi organic Calcium reactor.

Anyone here know the chemistry well enough to actually put some equations into this?

 

[Anonymous]

I was hit by a bit of a eureka moment last night, (bear with me this could be painfull). And anyway, i was thinking. You seem to have a very high Ca level, 400-450 is within the realms of a very well supplied system. I've heard of people with Kalkwasser Reactors and Calcium Reactors running in tandem, and only just manageing the same sort of level. And allthough ive heard very good things about b-ionic, i find it a little difficult to beleave that that alone could be responsible for the levels you have.

I thought I was doing well also.

You also say that your system expiriences huge PH drops at lights out, diminished Kh levels that are disproportional to the Ca usage of a regular balanced reef. (allthough i feel this 'balance' is meerly coincidental)

Yep ph does drop at night. Everything seems fine though.

Anywho, it seems that the large ammount of macros in the system are responsible for this imbalance. So that would also indicate that they are growing very well.

What imbalance? Things have stabilized to these values for months.

The large Ph drop at lights out must be due to the plants respiration, as im sure your well aware, plants photosynthasise by day, and respire at night, taking in Oxygen and releasing C02.

yep. and also why ph just before lights out rose from 7.4 before macros to 8.4 after. And has stayed there for well over a year.

Reef tanks, being heavily skimmed, will have an abundance of oxygen in the water, and very little C02 due to the aggitation and resulting dissipation by the skimmers air/water mix.

N/A no skimmer used.

This would be a bad situation for the plants during the day, but near on perfect conditions for nightly respiriation.

What im thinking is that the C02 relased by the plants during the night, due to the optimal conditions for respiration, is causing elevated levels of Ca to be released from the sand bed. Its as if your Ph drop assisted by the Co2 in releasing the Ca, a bit like super charging Kalkwasser with vinegar.

one fly on the ointment is my sand is silica play sand. And the rocks are lava type not the calcium carbonate based type.

Potentially, this could be another method of creating a natural system, with a semi organic Calcium reactor.

Anyone here know the chemistry well enough to actually put some equations into this?

I think you are really really close. Hint Hint from my second post in this thread

My 55g maintains 400 ppm cal and 2.5 kh alk with no additives. I do use crushed oyster shells in a diy filter box though and they did change it from 250-300 ca and 4 kh alk. so my alk did raise after the ca increase. perhaps that has happened to you also.

So my calcium rose from 250-300ppm to 400ppm in 3-4 weeks after I added crushed oyster shells to the system and had 5x/hour circulation flowing through those shells. So you may be right. a nightly ph drop may allow a slow dissolving of the shells. And with the circulation through the shells all the tank water has contact to allow a slow increase in calcium. And all of that is happening with 0-$20 of macros, a $5 DIY filter box from home depot, and $4 of oyster shells from the local feed and seed store. Oh yea the $4 is for 40 pounds of the shells which should last over a year. Plus the shells do mechanical filtering as well. And to top all that off the calcium rose to 400-420 and stayed there. so no worry about the level getting to high. And ph can never go high as in dripping kalk.

Plus the entire system uses aerobic methods. No anaerobic bacteria required. Additionally, the macros and macros only can stop mini cycles from various bumps in the night. The aerobic bacteria are helpful in processing wastes and very important. But not totally necessary as the plant life also prefers to consume ammonia directly if given a chance.


As I said, think I'll just let it be.

 

[Mouse]

I wouldn't change anything either...... except

Im just trying to figure out whats actually happening, in an allbeit Mousey laymans kinda way. But another thing you may be interested in, your crushed oyster shell, if what you say about the flow is correct, will become the perfect place for sponges to grow. They grow best in the dark, and if you laid them out, surface area wise, they would beat any kinda filtration on the market. If you were to change anything, i would suggest you might want to add MORE oyster shells, just enough to cut out light to the middle to lower levels, i dont think your going to get anerobic in oyster shell no matter what the depth, but cutting out the light to encourage the growth of sponges could be of benefit.

 

[Anonymous]

interesting. I do have some white sponge type things growing on the landscape lave rock I use at the entrance and exit of the filter box.

The box is also in my external sump/refug and there is a 18 watt NO spot there for the macro. And the oyster shells do turn green in about a week or so. So there is some micro algaes growing.

I am building a new "filter/surge" from PVC. Which no light can enter to the shells. The idea is to replace the external flood capable sump/refug. So have to wait to see what happens.


So I guess I am changing things after all 8O . But hopefully the basic operation will remain the same.

 

[Mouse]

Good luck, post the results

 

[Mihai]

Man, I suck so bad!

Have a look at the initial post and at this article at RC:

http://reefkeeping.com/issues/2004-12/rhf/index.htm

"One of the most common complaints of new aquarists is that their aquaria seem to need more alkalinity than their balanced additive system, such as limewater, is supplying."

That would be me

The explanation is super-simple:

"One of the interesting features of seawater is that it contains a lot more calcium than alkalinity. By this I mean that if all of the calcium in seawater (420 ppm; 10.5 meq/L) were to be precipitated as calcium carbonate, it would consume 21 meq/L of alkalinity (nearly 10 times as much as is present in natural seawater)."

That means that I don't have an inbalance, just that the Ca got lower only a little bit compared with the calcium!

I'm posting this in the hope it will help other noobs.
M.

 

[Oceans Ferevh]

beaslbob, I know that you don't care to change anything, but just as a though for the future, if you do dicide you want your PH to maintain more stable parameters just try keeping your macro lights on 24/7. I'm new to this like Mihai, but no resperation equals no PH fluctuations. Am I right? At least that's what I've been doing with my Macros

 

[Rlumenator]

Mouse- I use a 2 part doser and also experience an alk. drop from time to time. How much baking soda to use? I have a 155 gal, after live rock water displacement- I'd guess 100 gal. water. Thanks.

 

[ZooKeeper1]

Mouse I'm wondering why you feel that dissolved sand only supplys calcium. Of corse alkalinity is added as well In the same 1 meq/l alk : 20 ppm calcium ratio as other balanced additives.
And what about this GH,KH stuff ? GH is basicly used for fresh water, but in salt it is basically the same as the caco3 test without the mag. precipitation first.
Id say that your right about the plants , because they are using nitrates wich use alkalinity in their conversion from nitrite. But probably most of the problem lies in not supplying enough balanced addative in the first place.

 

[Anonymous]

beaslbob, I know that you don't care to change anything, but just as a though for the future, if you do dicide you want your PH to maintain more stable parameters just try keeping your macro lights on 24/7. I'm new to this like Mihai, but no resperation equals no PH fluctuations. Am I right? At least that's what I've been doing with my Macros

Yes you are correct. And most people posting do run 24/7 or reverse display periods to help maintain a constant ph.

My system maintains unmeasurable levels of ammonia, nitrIte, and nitrAte, plus ca at 400ppm alk at 2.0 meg/l. just before lights out ph is 8.4 just before lights on 7.4-7.7. Those valuse appear to be rock solid and and everything is thriving including a couple of SPSs.

In my opinion it is not required nor does it even appear to be desirable to maintain constant ph. As long as in a 24 hour period the ph recovers that means the carbon dioxide in the system is being consumed. And the plant life is helping filter out toxins and heavy metals and even maintaining ALK.

I simply don't want to interfer with a stable extablished system.

The fact it only costs $100 to setup a 55g system is just an added plus.

 

[ZooKeeper1]

how are your plants maintaining alkalinity?

 

[Anonymous]

how are your plants maintaining alkalinity?

Basically the ammonia-nitrate bacterial conversion uses up a carbonate ion and the plant life consuming the nitrAtes returns the carbonate ion.

Ref:
in this article: http://reefkeeping.com/issues/2004-12/rhf/index.htm of reefkeeping, Dr holmes-farley explains:

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

So ammonia to nitrate depletes alk. But:

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 -> 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- -> C106H260O106N16 + 138 O2 + 16 HCO3-

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

So actually either anaerobic bacteria (DSB) or plant life can return the carbonate ion.

And further in the article:

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.

In my systems I use plant life and no water changes. Combining both effects.

This article also confirms one aspect of my experience. Plant life with no water changes = stable system requiring no dosing. I also have 5x water flow through crushed oyster shells which makes calcium carbonate available to the system.

And further. I use tap water which probably has a small amount of nitrates in it. From the above article my plant life consumes those nitrates and still returns the carbonate ion. Without having consumed that ion in the ammonia to nitrate process. Therefore, plant life and tap water add carbonate ions to the system.

 

[ZooKeeper1]

That doesn't mean plants maintain alkalinity in a reef tank. Dont you have other things in there consuming alkalinity.

 

[Anonymous]

That doesn't mean plants maintain alkalinity in a reef tank. Dont you have other things in there consuming alkalinity.

Sure.


But it does mean that alk will be higher:


1) with plant life then without plant life.

2) with no water changes then with water changes.

3) with tap water than with ro/di

Additionally, tap usually has some calcium carbonate in it to further raise ALK. But alk will be higher if there is any nitrAtes in the tap regardless of the presence of calcium carbonate in the tap.


Then when I pump the water through my crushed oyster shells, calcium rose to and has stayed at 400ppm and alk is 2.0 meg/L. But as Dr. holmes-farley pointed out above you very well could lose 1.6 meg/l per year by maintaing the system with water changes and no plant life.

 

[ZooKeeper1]

Yes but does that make them good practices? Plants are the only thing I can agree with there. The others, alk is to cheap to justify that.
I maintained alk higher than 2 in a softie tank using aragamight in a topoff reservoir with distillede.