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

[AllSignsPointToFish]

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.

Does the baking process convert some of the bicarbonate to carbonate?

 

[AllSignsPointToFish]

Does the baking process convert some of the bicarbonate to carbonate?

Duh. I should've thought this through. Sodium bicarbonate (i.e., baking soda) is used as a leavening agent in baking because to decomposes to from carbon dioxide and sodium carbonate when heated in the oven. Boneheaded. LOL

 

[mcarroll]

It seems like #2 could be seen as more-than-fine in my particular case. Doesn't you think it has some qualities that would recommend it in this scenario?

Is this what you're saying by your quote? Or are you kind of differing with that point of view?

I'm not totally sure what you meant by the quote within the context.

That's the passage on which I based my whole dosing system from Day 1, so on one level it explains everything I did and everything I do. (Even before I actually DIY'd my reagents, but obviously starting with Recipe 1 and even the switch to #2.)

Seems like once my coral growth got to a certain level I should maybe have had a plan to switch to Recipe #2 if I wasn't going to setup some kind of pH monitor or automated dosing system.

Would you agree with that?

 

[mcarroll]

Does the baking process convert some of the bicarbonate to carbonate?

Cleaning burnt stuff off of kitchen pans is a nice alternate use for this chemistry.

Burnt pan + baking soda + boiling water (any order) = unstuck burnt stuff

It's like cleaning magic. Just be prepared for some bubbles – don't use too much water!

 

[Randy Holmes-Farley]

I guess I still think exactly what I wrote in that article originally, and if folks have preciptiation issues, a lower pH can be helpful since it reduces the supersaturation of calcium carbonate.

 

[biom]

My tank is full of SPS, current daily alk consumption about 3 dkH, only sodium carbonate is used from the beginning, almost all corals are grown from tiny frags. No problems with precipitation, no problems with high pH - actually it was as low as 7.8-7.9 lately (very cold winter here), so I was forced to ensure some fresh air to skimmer from outside. Dosing with autodosers.

 

[mcarroll]

My tank is full of SPS, current daily alk consumption about 3 dkH, only sodium carbonate is used from the beginning, almost all corals are grown from tiny frags. No problems with precipitation, no problems with high pH - actually it was as low as 7.8-7.9 lately (very cold winter here), so I was forced to ensure some fresh air to skimmer from outside. Dosing with autodosers.

Of course.

 

[Joey Vagneur]

Randy please help. I have stopped all dosing. I am testing daily. I have not dosed in 5 days. My calcium is at 460-470. It is holding there and is not going down at all. Mag is at 1400 and alk is at 5 dkh. It held there.

After 3 days of 5 dkh measure with 2 different tests I decided to add Alk. I did at night tested and it went from 5 - 6.8 was going to add more the next day to hit a 8.2 target.

Tested in the am.. back at 5.

I am super concerned, as I thought calcium would be dropping a bit but it's not

 

[mcarroll]

Are you still seeing physical signs of precipitation in the tank?

I wish I could say that something besides a strong combination of elbow grease and cursing worked for me.....it was a few months like that from my recollection.

 

[Joey Vagneur]

Yes my sump is seeing build up. I am switching into a 300 gallon. All new plumbing and equipment, I fear I will have this issue with the new tank if I port over rock and water so I don't have to cycle.. if I do not need to worry about it I see me just breaking down the tank soon

 

[mcarroll]

Just keep the rock by itself and keep it running so it's ready for the 300.

It will eventually get covered in Mg and P crystals, a biofilm will form and it'll stop precipitating.

I'd consider switching it to a fowlr before I'd do a premature teardown.

 

[Randy Holmes-Farley]

Randy please help. I have stopped all dosing. I am testing daily. I have not dosed in 5 days. My calcium is at 460-470. It is holding there and is not going down at all. Mag is at 1400 and alk is at 5 dkh. It held there.

After 3 days of 5 dkh measure with 2 different tests I decided to add Alk. I did at night tested and it went from 5 - 6.8 was going to add more the next day to hit a 8.2 target.

Tested in the am.. back at 5.

I am super concerned, as I thought calcium would be dropping a bit but it's not

Calcium won't drop noticeably for small alk changes, and cant drop much at all if alk is 5 dKH.

What are you dosing for alk?

 

[Biznizface]

Just read this as I'm having a problem with precipitation cannot get my alk above 6-6.5.

Mag is 1350 calcium 400.

A couple of months ago I over did it with alk and cal adding far to much of each. My pumps and powerheads kept seizing up.

I was adding to much Sodium carbonate and calcium chloride mixes respectively.

A friend advised me to stop dosing calc for a while and add 2 thirds less of alk which I did and I went from over 300ml of alk to where it is now 140ml but still can't get dkh above 6-6.5 ?!

I have 220 litres total volume my PH is stable at around 8-8.2 (salifert)

My sand bed is coarse (big mistake) and has been clumping together which I gather is the precipitation.
The last two water changes I have removed a lot of the sand and am going to gradually remove all the sand within the next few weeks.
My pumps are not seizing anymore but the walls of my sump are coated in a white flaky stuff and my heater has always got flakes on it but not as bad as before.

Still cannot get alk above 6-6.5 I am at my wits end I'm dosing 140ml of alk and 90ml of calc and 50ml of mag hexahydrate chloride daily.

Anyone know how I can get over this have lovely sps frags that I fear losing if I can't get to the bottom of this ?

 

[Randy Holmes-Farley]

The ways to reduce precipitation, in addition to dosing nothing for a while and let the surfaces get clogged with organics, magnesium, and such are to:

1. Dose sodium bicarbonate instead of carbonate
2. Dilute the dosing fluid
3. Spread out the dosing as much as possible
4. Stop using GFO (if you are).
5. Let the pH drop, keep magnesium high, don't as heavily export organics, and don't drop phosphate too low (or let it rise a bit)

 

[Biznizface]

The ways to reduce precipitation, in addition to dosing nothing for a while and let the surfaces get clogged with organics, magnesium, and such are to:

1. Dose sodium bicarbonate instead of carbonate
2. Dilute the dosing fluid
3. Spread out the dosing as much as possible
4. Stop using GFO (if you are).
5. Let the pH drop, keep magnesium high, don't as heavily export organics, and don't drop phosphate too low (or let it rise a bit)

I dose the alk every hour with my doser, cal every two hours etc.

Are you saying not to dose anything for how long a day or two days ? Longer ?

I can swap to bicarbonate.

I use Fauna Marin balling recipe for my dosing salts.

So when you say dilute the mixes do you mean instead of 500g for 5 litres of alk do say 300g for example or what would you say ?

I've been using Seachem Phosguard in a reactor if I stop for how long ?

I also run 5 litres of siporax in an egg crate basket not sure if I've clogged it with precipitation?

Nitrate is around 10ppm, phos is 0.02 approx.

 

[Randy Holmes-Farley]

It is tricky to stop because will will get pretty low in an SPS system, but a few days would be best from a precipitation standpoint.

By dilution, I mean instead of adding, say 10 mL each dose, dilute the solution with 1 part of the current solution and 9 parts of fresh water. Then add 100 ml each dose. OR some such thing. Even a factor of two may help.

The switch to bicarbonate may help the most, since higher pH is a massive driver of precipitation.

Do you know what the phosphate level is?

 

[Biznizface]

The phos level is 0-0.02 not sure am using Elos high res kit but hard to tell if I'm 0 or just above.

I have been using sodium carbonate but do have this one to hand

Not sure if it's also carbonate or a mixture.

I have been using food grade carbonate not branded.

So would you dilute the current solution or swap to the branded salt above ?

What about if I just stopped dosing cal and mag for a few days and alk for say one day ?

 

[Randy Holmes-Farley]

I'd switch to grocery store baking soda.

It is the alk dosing to stop. The others don't matter.

 

[Biznizface]

I'd switch to grocery store baking soda.

It is the alk dosing to stop. The others don't matter.

So stop dosing until alk until Sunday but carry on with the cal dosing or stop all dosing ?

Shall I do a water change before say just over 10% is ok ?

Then on Sunday using baking soda build up slowly to 7dkh ?

So what dilution into 2 litres of RO for the baking soda also ? How much baking soda into 2 litres of RO ?

 

[NewYorkReefer1988]

I have been having the same issue for the last 3 months and it’s driving me crazy. I’ve done just about everything you did and still no luck. I even stopped dosing entirely and turned over about 300% of my water with water changes and still no luck. I just can’t get over 7 DKH. The only think I haven’t done is a 100% clean out of the crust in my sump. Could this my the root cause as to why the issue keeps hanging around?