Alk precipitation....anyone else been through this?

[Randy Holmes-Farley Verified Community Expert]

I am having the same problem. same thing kicked it off. too much alk that caused alot of percipertation, now I can't get the alk to take. it just keeps percipertating onto the equiipment. mag is 1360, cal is 430. but alk can't get it above 9.6 and that's with 135ml of soda ash a day. there is no load on the tank since it is brand new. no corals or inverts.

anyway the reason i;'m posting is "what is recipe 2???? I did a couple of water changes, and did the scraping and vinegar with the tank and equipment but even when I switch to bi carbonate it still won't go higher than in thje 9's. and that's with either 135 ml of soda ash or 280 ml of bi carbonate

Stop dosing alkalinity for a few days and let it decline. That slows and stops precipitation, allowing organics, magnesium and phosphate to coat existing calcium carbonate surfaces and preventing them from being sites for additional precipitation.

 

[mcarroll]

Most people do not get excessive pH using sodium carbonate. I'm not convinced you did either unless you dosed too fast.

Isn't it equally true then that Recipe #2 would not get excessively low pH using bicarbonate?

Anyway, it's a little late for second guessing – except for a brief switch to ESV, I've been using Recipe #2 exclusively since then.

As I said back then at the time, I don't monitor pH so I never did know for sure it was a pH spike....it still sounded reasonable, logical and likely though, so I just took the advice. And it has worked out!

(Almost forgot about this thread.....I really thought I remembered that I got feedback from you directly. But all I see is where I looked at your article on precipitation....huh. That must have been before I banned "that other place" and maybe that's where I got your feedback. When did you come to R2R again? I might have to go look up my old posts there. )

 

[fishkeeper2]

Just for the benefit of others reading this post: Alkalinity, or Total Alkalinity (TA), is defined as a measure of how much acid (H*) is needed to lower the pH of the water to the point where all bicarbonate can be converted to acid. This point rests at about 4.2 in sea water.

Consequently, alkalinity tests try to determine how much acid is required to lower the pH to the 4 - 5 range. The pH drops faster in water that has poor or no buffering capability. When you are testing you are actually putting drops of acid into the vial to determine when the color changes, meaning when it reaches 4 - 5. The measurement unit varies by test kit. Most like to test for the amount of calcium bicarbonate. 2.0 meq/L refers to milliequivalents per liter. Some tests test for borate.

Sea water has multiple chemicals which help buffer pH. These are in order of effectiveness: bicarbonate, carbonate, borate, silicate, magnesium monohydroxylate, hydroxide, and phosphate.

Adding too much calcium supplement can drive down alkalinity due to the precipitation of calcium carbonate in the tank. Likewise, adding too much of an alkalinity supplement can result in a reduction to calcium.

The question is exactly what were you adding? If you added a balanced calcium and bicarbonate additive then by adding too much your pH should have stayed 7.9-8.5 and you saw lots of white precipitation. That was most likely deposits of calcium bicarbonate, depending on your additive.

Magnesium plays an important role in preventing cal bicarbonate precipitation but it seems that mg was fine at around 1100-1300ppm.

Did you try adding just a calcium additive to try to bring the calcium and alkalinity in balance?

What was your pH during this event?

There was an ionic imbalance in your tank which results in the cloudiness and precipitation of white residue. Most people get rid of it by either gradual water changes or attempting to bring the calcium and alkalinity in line with one another given that you already had good mg.

I switched to Seachem marine/reef buffer for pH stability and Red Sea ABC+ additive for calcium/mg/alk etc. No issues after that.

 

[Randy Holmes-Farley Verified Community Expert]

Isn't it equally true then that Recipe #2 would not get excessively low pH using bicarbonate?

Anyway, it's a little late for second guessing – except for a brief switch to ESV, I've been using Recipe #2 exclusively since then.

Correct, dosing bicarbonate will not cause low pH. It also won't help prevent low pH caused by CO2 in the room air.

 

[mcarroll]

Where possible, it seems like fresh air or CO2 absorbing media seem safer, more predictable bets at preventing low pH/dealing with excess CO2.

I always thought it was funny to hear people with CO2 buildup in their house take their baking soda and bake in in the oven – releasing additional CO2 into the house. CO2 is a problem already, so it's apparently not going anywhere else.

Heating baking soda in one of these houses seems like it would add to the problem in the long run vs curing it.

Household CO2 issues aside, for anyone dosing in large quantities of two-part (i.e. with a loaded coral system like mine was) it seems like Recipe #2 is a better bet – especially if you're DIY'ing your reagents since no oven processing is needed.

Even though I had very controlled additions for dripping and a long track record (5 years) of no problems, I still ended up with an event when using Recipe 1. Even if that was becase I added it too fast, Recipe 2 might have prevented it from happening.

Looking back I wish I'd been using Recipe 2 the whole time. Cheaper, easier and better, at least along these lines.

 

[mcarroll]

Nothing on the other site about this from me, so I guess I'm just thinking of something else I asked you back in the day.

(Still can't figure why I have such a specific answer from you in my head though. Ah well!)

 

[Randy Holmes-Farley Verified Community Expert]

Where possible, it seems like fresh air or CO2 absorbing media seem safer, more predictable bets at preventing low pH/dealing with excess CO2.
.

It is only more predictable if you don't know the prediction for sodium carbonate. lol

I know exactly how much sodium carbonate raises pH per unit of alk added (I've measured it), but I don't know how much CO2 absorbing media boosts pH because it depends on the relative tank top and skimmer aeration.

 

[mcarroll]

I know exactly how much

pH Correction
But even if we all knew that by heart, the pH range of the water we're treating can vary from house to house though. Of course the Recipe 1 dose will vary over the course of the tank too. Don't those two variances make it a coincidence if someone's CO2 problem is actually taken care of vs being more or less over or under?

Also because of house to house variability, it seems like at least some of us without household CO2 issues would at least be somewhat likely to run into problems when we have a tank full of stony corals drawing down CO2 and we're dosing mass quantities of Recipe 1 (also sucking up CO2) though. No?

CO2 management
While I'm asking, how much CO2 would one 250mL dose of Recipe 1 alk remove from a tank?
(From memory this is the amount I was dosing back in the day....but it's a nice, round number to think about regardless.)

I have wondered for a while if Recipe 1 adds up for the DIYer who has a household CO2 problem. They're putting the CO2 from the baking soda into their own house where (at least I think) it ends up as a higher ppm of CO2 in the house. (Wouldn't it?)

Doesn't higher ppm of CO2 in the house in-turn make the CO2 problem in the tank worse over time? Where this is not someone's only option for eliminating CO2 from the tank, it seems like other solutions would be preferable.

With something like TLF's CO2 product, I guess the CO2 gets thrown out with the trash.

With an outside air connection to the skimmer, the skimmer is being consistently bubbled with "unpolluted" air. I supposed this must displace some of the air in the house. My skimmer can draw almost 160 GPH of air according to the mfgr. If I have a 2000 square foot house, maybe we can assume a volume around 20,000 cu ft. I think that's about 150,000 gallons.

Unless I've screwed up the figuring, it would only take 937 days to exchange all the air in the house this way. Sounds like a lot of days (2.5 years), but considering the size of our skimmers (mine is small....a Tunze 9410) it's actually a little impressice! (Opening doors, etc, counts too....this is just an example!)

So anway, I guess a skimmer like mine might displace 1/937 (aka 160 gallons) of the "polluted" air in a house every day.

What (Else) To Do?
Interestingly for the household-CO2-problem people, P3 International now makes a Kill A Watt® Edge that has a CO2 monitor built in! Seems like that could eliminate the guesswork for them at least!
(Only $60/free shipping. Not that I shop for them often, but I've never seen a CO2 monitor under $xxx.)

For me and other non-problem-CO2 people (lol...my house is like swiss cheese) who might be dosing Recipe 1, it seems like running a pH monitor is the only way to know if your CO2 situation in the tank is borderline or not. Am I missing something there? If not, does that kinda leave the (safe) choice as Recipe 1+pH monitor or just Recipe 2?

 

[Randy Holmes-Farley Verified Community Expert]

I'll just say I have NEVER seen a reef tank where the pH runs too high (IMO) from appropriate dosing of sodium carbonate unless limewater is also being used. Most often, it is not adequate for bringing CO2 levels up to outdoor equivalent levels.

Limewater (kalkwasser) has slightly more than TWICE the pH raising effect of sodium carbonate, and it too can be dosed acceptably, assuming the tank is appropriately aerated.

A skimmer air inlet connected to the outside is not trying to bring down the house CO2 level, just the tank CO2 level.

The effect of adding 0.5 meq/L (1.4 dKH) of each of the following had the following instantaneous pH effects, starting at pH 8.1 and alkalinity of 2.26 meq/L (6.3 dKH) :

none 0.00 pH units
bicarbonate -0.04 pH units
carbonate + 0.34 pH units
hydroxide + 0.66 pH units
H+ (acid) - 1.19 pH units

after aeration the pH at equilibrium was the same for each of the alkalinity additions.


which is from:
Chemistry And The Aquarium: The Relationship Between Alkalinity And pH ? Advanced Aquarist | Aquarist Magazine and Blog
http://www.advancedaquarist.com/issues/may2002/chem.htm

 

[mcarroll]

The effect of adding 0.5 meq/L (1.4 dKH) of each of the following had the following instantaneous pH effects, starting at pH 8.1 and alkalinity of 2.26 meq/L (6.3 dKH) :

none 0.00 pH units
bicarbonate -0.04 pH units
carbonate + 0.34 pH units
hydroxide + 0.66 pH units
H+ (acid) - 1.19 pH units

Appropriate is relative....folks have to dose what they have to dose to keep levels up. A tank full of stony corals has real needs.

Personally, I'd like to think that a tank full of stony corals grown from frags over around five years time without any setbacks counts as some kind of success. And I used Recipe 1 through the bulk of that time....so it sure seemed appropriate to me....until it didn't.

So, a more realistic amount to talk about would be a 1 meq/L bump, which would take:
...about 200mL of Recipe 1.
...about 400mL of Recipe 2.

Is there simply no advice when you get to this level of dosing/success, or do we say that level of dosing is inappropriate?

I got to this point using manual drippers and paying attention while dosing. Is that also inappropriate?

So if it's possible to think this through without simply saying it's inappropriate....doesn't a high level of consumption from a tank possibly change the CO2 situation and hence the advice?

 

[Randy Holmes-Farley Verified Community Expert]

Tons of people use that amount (1 meq/L/day or 2.8 dKH per day) or more. I suspect that at least 5-10% of reefers on this forum use 1 meq/l/day of carbonate dosing without having excessive pH.

Usually they spread out the dosing to multiple times and the pH does not get too high, although the more pressing concern is likely alkalinity stability, not pH stability.

 

[mcarroll]

So it would have been better/safer at such a high dosage rate if I had had an [automated doser+Recipe 1] OR [a pH monitor+Recipe 1] ...but it seems like [just Recipe 2] is sort of equal in effect but simpler.

I was manually drip-dosing....it was the reality I had.

Dosers were absurdly priced and quite junky on the lower end when I started, and since the manual drippers I made always worked I never switched to an automated doser until a year or two ago. (The DIY attempt in this thread did not last long.)

Things are so different these days where you can get a three or four head doser for under $100.

When you see how many problems people get into from watching pH you want to just keep on not watching pH like I have...being limited on funds encourages this position. But I admit that I would really love to go back in time with a pH pen so I could know whether it did or didn't spike on that dose.

 

[Joey Vagneur]

Randy I had spoken with you on another tread about this. I stopped for 3 days and my Alka was at 5.5 I was worried my SPS would suffer so I went back to dosing.

I will say that only when I switched from recipe #2 did I experience this. It has been really hard to stop, without hurting the coral. I am not sure why as even BRS sales their 2part as soda ash...

I honestly do not know what to do at this point.

 

[Joey Vagneur]

I don't recall a ph spike either. As I use an apex and it alerts me

 

[Randy Holmes-Farley Verified Community Expert]

So it would have been better/safer at such a high dosage rate if I had had an [automated doser+Recipe 1] OR [a pH monitor+Recipe 1] ...but it seems like [just Recipe 2] is sort of equal in effect but simpler.

In my opinion, most people benefit more from carbonate dosing because their pH is most often lower than optimal.

 

[Randy Holmes-Farley Verified Community Expert]

I don't recall a ph spike either. As I use an apex and it alerts me

What is the typical pH?

 

[mcarroll]

In my opinion, most people benefit more from carbonate dosing because their pH is most often lower than optimal.

No argument there, but I was referring to my own 5-10% case in the example you quoted.

Even so, it hardly seems that bicarbonate dosing would hurt most people given it has such a low negative contribution to pH. Maybe in the extreme cases? But how many tanks have a native pH that low? Maybe also 5-10% you think?

On my side of the question, most people just don't have a tank-full (everything grown to the surface; almost no empty space left in the tank) of stony corals drawing on the system's CO2. Not that they've grown up "by hand" without an auto-doser.

For my context (or others like it), it seemed like maybe my "equation" you quoted was approximately accurate. Do you think?

 

[Joey Vagneur]

This is why I switched.. just need to figure out why I have more precipitation

 

[mcarroll]

Stop dosing alkalinity for a few days and let it decline. That slows and stops precipitation, allowing organics, magnesium and phosphate to coat existing calcium carbonate surfaces and preventing them from being sites for additional precipitation.

@Joey Vagneur I like Randy's idea. You just have a lot of naked calcium carbonate crystals in the tank.

Just take it easy, keep after the precipitation where it matters (pumps and heaters!!!) and don't expect instant results so you don't get frustrated.

 

[Randy Holmes-Farley Verified Community Expert]

No argument there, but I was referring to my own 5-10% case in the example you quoted.

Even so, it hardly seems that bicarbonate dosing would hurt most people given it has such a low negative contribution to pH. Maybe in the extreme cases? But how many tanks have a native pH that low? Maybe also 5-10% you think?

On my side of the question, most people just don't have a tank-full (everything grown to the surface; almost no empty space left in the tank) of stony corals drawing on the system's CO2. Not that they've grown up "by hand" without an auto-doser.

For my context (or others like it), it seemed like maybe my "equation" you quoted was approximately accurate. Do you think?

It is certainly fine to dose bicarbonate. That is why my recipes article makes this recommendation:

Comparing the Two Primary Recipes

This article actually details two primary recipes. One uses raw baking soda, and the other uses baking soda that aquarists bake before use. The baking drives some of the carbon dioxide out of the baking soda, and raises its pH as well as its alkalinity. Be careful about substituting other brands for the Dowflake and the magnesium chloride sold by the Dead Sea Works company. A later section in this article details substitution issues.

Recipe #1 is for use in reef aquaria whose pH is normal to low. In practice, more reef aquarists end up choosing this recipe than Recipe #2. It will tend to raise pH due to its alkalinity part's elevated pH, as do most of the commercial two-part additives. The increase in pH depends on the aquarium's alkalinity and, of course, on how much is added. Adding on the order of 0.5 meq/L of alkalinity increases the pH by about 0.3 pH units immediately upon its addition (and even higher, locally, before it has a chance to mix throughout the aquarium).

If you are using limewater (kalkwasser) and the aquarium is at pH 8.4 or above, this recipe is not the best choice. Otherwise, it is likely to be a good option. It is twice as concentrated as Recipe #2, because the baking process makes the baking soda more soluble.

Recipe #2 is for use in reef aquaria whose pH is on the high side (above 8.3 or so). It will have a very small pH lowering effect when initially added. The pH drop achieved will depend on the aquarium's alkalinity and, of course, on how much is added. Adding on the order of 0.5 meq/L of alkalinity drops the pH by about 0.04 pH units immediately upon its addition.

If you are using limewater (kalkwasser) and the aquarium is at pH 8.4 or above, this recipe may be the best choice. It is half as concentrated as Recipe #1 because the raw baking soda is less soluble because it's unbaked.