Limewater vs two part

[DBR_Reef]

Basically if you are doing sufficient water changes it can be enough to maintain Magnesium alone unlike 2 part where it is required.

I'm don't have a pad and pen to do the calculations right now, but I don't think there should be an appreciable difference in the need to add magnesium between kalk and two part. Both are adding bicarbonate and calcium ions. While 2 part also adds sodium ions, I don't think the dilution of magnesium would be significant, but I haven't done the calculation, so it is possible I am wrong. The largest sink for magnesium thought is its precipitation, and I believe that would happen equally quickly using either method.

 

[bif24701]

I'm don't have a pad and pen to do the calculations right now, but I don't think there should be an appreciable difference in the need to add magnesium between kalk and two part. Both are adding bicarbonate and calcium ions. While 2 part also adds sodium ions, I don't think the dilution of magnesium would be significant, but I haven't done the calculation, so it is possible I am wrong. The largest sink for magnesium thought is its precipitation, and I believe that would happen equally quickly using either method.

Could be, I'm not an expert on 2 part but seems that Mag supplementation is strongly recommended with 2 part as opposed to Kalk.

 

[DMan]

Stated in the article:

"As expected, the magnesium depletion is significant. While this depletion may be mitigated in a number of ways (including water changes), it shows that aquarists using limewater should consider monitoring magnesium over long periods of time. The previous article also compared magnesium depletion via limewater to magnesium depletion using a variety of different calcium carbonate materials in CaCO3/CO2 reactors."


Basically if you are doing sufficient water changes it can be enough to maintain Magnesium alone unlike 2 part where it is required.

Totally agree. I think over the past year I've had to make an adjustment to the Mg. twice as it fell a bit. But other than that w/c kept it stable.
And same goes for the 2-3 part additive. Maybe a bit slower rate though. Can't remember quite what it was. Something like for every gallon of 2 part you added a couple of cups of the 3a/b recipe.

 

[jason2459]

Afaik the only recommendation for Mg between using 2 part and kalk is just the ratio of Mg Sulfate to Mg Chloride. Otherwise the recommendation is the same. Dose as needed or not at all. I add about 4oz to my new saltmix that lasts a couple weeks changing around 1% daily.

Otherwise I don't know enough about 2 part other then some light reading of Randy's articles which I know answers all the questions above and suggest looking at them.

Limewater takes care of all my needs. If it ever did not I would continue using limewater at the constant rate I do now and supplement with 2 part. Limewater is my primary means of keeping my pH up. If someone had a issue with high pH with out dosing I would not suggest limewater but a Calcium reactor.

 

[bif24701]

Mag is needed with 2 part to balance the sodium and chloride ions. This is also part of why 2 part raises salinity over time.

 

[jason2459]

Mag is needed with 2 part to balance the sodium and chloride ions. This is also part of why 2 part raises salinity over time.

I'm not seeing that but I don't know enough about 2 part to know. Only that one recipe is preferred over the other and Mg is only calculated and dosed to make sure Mg is not depleted while corals build their skeletal structure. Not that Mg is required to balance out the 2 part itself.

http://www.reefkeeping.com/issues/2006-02/rhf/#6

"Additionally, we may want to account for magnesium that is actually incorporated into the coral skeletons. For this calculation, I have assumed that the amount of magnesium incorporated is about 6.5% of the calcium level (by weight), or about 2.5% of the skeleton by weight. In the course of adding this gallon of both parts of the two part supplement, we added 141 grams of calcium, so we need to add 0.065 x 141 = 9 grams of magnesium to account for this deposition.

The magnesium parts of the recipe are designed to add enough magnesium so that it is not depleted by either of the two means described above. Because the magnesium supplement (either version) is 47,000 mg/L in magnesium, we need to add (9 +19.5) grams/47 g/L = 610 ml of the magnesium solution for each gallon of the other parts of Recipe #1."

Which is the same reason to dose Mg if needed with limewater but there is also a different prefered ratio of Mg chloride vs sulfate.

http://reefkeeping.com/issues/2005-01/rhf/index.php#14

http://www.advancedaquarist.com/2003/10/chemistry

 

[bif24701]

I'm not seeing that but I don't know enough about 2 part to know. Only that one recipe is preferred over the other and Mg is only calculated and dosed to make sure Mg is not depleted while corals build their skeletal structure. Not that Mg is required to balance out the 2 part itself.

http://www.reefkeeping.com/issues/2006-02/rhf/#6

"Additionally, we may want to account for magnesium that is actually incorporated into the coral skeletons. For this calculation, I have assumed that the amount of magnesium incorporated is about 6.5% of the calcium level (by weight), or about 2.5% of the skeleton by weight. In the course of adding this gallon of both parts of the two part supplement, we added 141 grams of calcium, so we need to add 0.065 x 141 = 9 grams of magnesium to account for this deposition.

The magnesium parts of the recipe are designed to add enough magnesium so that it is not depleted by either of the two means described above. Because the magnesium supplement (either version) is 47,000 mg/L in magnesium, we need to add (9 +19.5) grams/47 g/L = 610 ml of the magnesium solution for each gallon of the other parts of Recipe #1."

Which is the same reason to dose Mg if needed with limewater but there is also a different prefered ratio of Mg chloride vs sulfate.

http://reefkeeping.com/issues/2005-01/rhf/index.php#14

http://www.advancedaquarist.com/2003/10/chemistry

I literally just posted a quote of the article and the link for reference.

Post #93

 

[jason2459]

I literally just posted a quote of the article and the link for reference.

Post #93

And we interpret it differently

 

[bif24701]

And we interpret it differently

How? I really don't know what you mean?

In fact just ignore me, I haven't used two part in over 8 years so I'm really not sure. That's just what I've always known.

 

[Kaba]

I run my dosing pump for my 2 part through my controller. I know how much my alk dose should spike my pH at it's highest point, so I set the controller to turn off the dosing pump if the pH goes 0.1 over that.

 

[Jizu Puentes]

I see no issue with this, you don't require full saturation but mixing it at capacity is easy.

Separating the two is also safe, and simple.

I advise you though never use the Aqualifter pump with Kalk. It is way too inconsistent and can/will siphon.

I actually do run at full saturation. Mixing it is definitely easy.

I figured that out about the Aqualifter quickly when I set it up so now I have the pump attached at the top of my sump higher than the tube in my ATO jug.

 

[BigJohnny]

This is what I do, dose Kalk with a brs peristaltic dosing pump. So much easier to only dose 1 (also cheaper) ingredient and always in proper proportions. The key is to adjust your alk/calc to ideal levels using 2 part (i just did this by hand) and then start the kalk drip. I dose mine spread out across the night to help maintain ph. I can easily adjust the dose with my reefkeeper. The advantage over the ATO method is that you dont have to worry about ruining ATO pumps, dosing more kalk just cause your evaporation goes up, or over dosing your tank when your ato wont turn off or something. I use a fully saturated solution so i can store almost a months worth in a dosing container.

 

[Randy Holmes-Farley Verified Community Expert]

Could be, I'm not an expert on 2 part but seems that Mag supplementation is strongly recommended with 2 part as opposed to Kalk.

Both may need it, but more magnesium (about twice as much) is required when using a two part that does not supply magnesium in one of the two parts. One portion offsets consumption but corals and such, and the other ensures that sodium (from the alk part) is not rising relative to magnesium.

 

[bif24701]

Both may need it, but more magnesium (about twice as much) is required when using a two part that does not supply magnesium in one of the two parts. One portion offsets consumption but corals and such, and the other ensures that sodium (from the alk part) is not rising relative to magnesium.

Thanks for the clarification.

Randy, is it because so much Magnesium is in salt water that consumption can often be replaced with water chnages

 

[Randy Holmes-Farley Verified Community Expert]

Thanks for the clarification.

Randy, is it because so much Magnesium is in salt water that consumption can often be replaced with water chnages

It may since demand is often low and many mixes have much higher than NSW levels. But that isn't the reason a two part needs more.

 

[bif24701]

It may since demand is often low and many mixes have much higher than NSW levels. But that isn't the reason a two part needs more.

No I get that. Mag is used to balance the sodium ions right.

 

[Randy Holmes-Farley Verified Community Expert]

No I get that. Mag is used to balance the sodium ions right.

Yes.

 

[jason2459]

Yes.

Interesting.

Does a person need to calculate out and worry about that balance if

1. That person is doing a regular water change, say 1% daily, and dosing a small amount of Mg to keep it maintained at 1300mg/L

2. That person does no water changes but monitors Mg and doses to maintain Mg at 1300mg/L.

3. That person does larger water change, does not dose any Mg, but it is maintained at 1300mg/L through water changes.

I can see how Mg is recommended in a 2 part system but is it required above and beyond dosing Mg above recommended ranges for Mg to be in? Which to me would be the same requirement for when using limewater.

Wrapping my head around it as I've always simply used lime.

 

[Randy Holmes-Farley Verified Community Expert]

The target level of magnesium is no different. It is just that the amount needed to maintain that same target level is different for the same amount of calcium/alk dosed via limewater and dosed via Na2CO3/CaCl2.

Water changes may reduce the amount needed both to offset calcification consumption and the amount to balance the NaCl accumulation IF the magnesium is at or above the tank target level, and will increase the amounts needed if the new water magnesium level is below the target level.

 

[Randy Holmes-Farley Verified Community Expert]

FWIW, this is a bit complicated, but I know you like details...

If you add the magnesium in a bolus IMMEDIATELY AFTER a water change (with water that matches the tank target), the magnesium will climb because the mangesium was a bit low before the water change, climbed a bit during the change, then climbed a bit more after the bolus to a level slightly higher than the target.

If you add the magnesium in a bolus IMMEDIATELY BEFORE a water change (with water that matches the tank target), the magnesium will stay steady because the magnesium should be exactly at the tank target before and after the water change.

If you add magnesium very frequently and do water changes very frequently, the effect will be tiny either way as the levels will always stay near the target level.