2 Part dosing, Calcium/Alkalinity uptake questions

[ViktorVaughn]

I started my tank 9 months ago yesterday and have recently seen my tanks Calcium and Alkalinity usage go way up since its inception which I suppose is normal after frags become colonies and more coral is added. I slowly added pieces, zoanthids and some LPS at first with some SPS coming a little later, perhaps 4-5 months after tank was started. For the first 7 months or so, Calcium was maintained between 420-450 with bi-weekly 20% water changes on a 52 gallon total system volume set-up (40 breeder with 20 gallon sump that has ~12 gallon of water). Alkalinity would slowly drop between water changes but dosing would be minimal, perhaps a need for one .5 dkh boost in between.

Equipment, Parameters, Coral List
40 Breeder tank, 20 Tall sump with ~12 gallons of water
-Reef Octopus BH1000 Skimmer
-Phosban 150 reactor with 50 grams of Phosban tumbled, changed monthly
-Two 150 Heaters
-5 gallon DSB refugium with ~10 lbs live rock, large clump of Chaeto
-1.025 salinity, 77 Fahrenheit, 8.7-9 dkh, 440-450 ppm Calcium, 1350 ppm Mag, 8.0-8.2 ph, Undetectable Nitrates and Phosphates, 0 ppm Nitrites, Ammonia
Corals: SPS: Large Birdsnest and Medium Birdsnest, 2 medium sized Montipora Caps, 2 Medium Digitatas, 4-2" Acropora Frags LPS: Large Duncan, 2 4" Favias, 5" elegance, 3 small 2" Chalices Zoanthids: 3 100+ colonies plus maybe 20 ish 10-20 polyp frags Mushrooms: Green Striped Mushroom Rock, Two small Rhodactis

Since I have recently (2 months or so) seen a need to dose to keep my levels consistent and at acceptable levels, I have been using Fluval Sea Alkalinity and Calcium for dosing, which I don't know if is the best best brand to use or not. The ingredients for each are; Calcium: USP grade Calcium Chloride and Alk: USP Grade Sodium Carbonate, Bicarbonate, and Borate. The concentration for each is not listed. The directions for Alkalinity say that 10 ml/13 gallon of system volume brings the dkh up 1.4, or 40 ml for my 52 gallon volume. I am currently using 30 ml per day, 15 ml in the morning before I leave for work and 15 ml when I get home. That is 3/4 of the dose that brings up the dkh 1.4 so I calculated that my tank uses up 1.05 dkh a day. As for the calcium dosing instructions and levels that it is raised by said doses, 5 ml of the Calcium solution per 20 gallons of system volume raises the tanks levels by 10 ppm so I am using 12.5 ml/day which I add two hours after the post work Alk dosing. To arrive at the doses I use and I measured the tanks Calcium and Alkalinity levels for 3 days at the same time with no dosing in those three days.

My questions are related to my dosing regimen and the rates at which Calcium and Alkalinity are being used up and also the planned pumps I am looking at. Do my levels of consumption for each Calcium and Alkalinity seem normal? What about the relationship between the two (1.05 dkh/.375 meq/l Alk and 10 ppm Calcium a day)? I have read that they should theoretically be used at a rate of 1:1 and not sure where mine falls. Since I am needing to add 1.05 dkh a day and 10 ppm of Calcium, I want to spread out the dosing of each so it isn't just two big jumps of .575 and a 10 ppm of Calcium when I dose it all at once. I am planning on adding either the BRS 1.1 ml/day dosing pumps or the Bubble Magus 3 channel dosing pump to make for a nice steady drip of each making for a nice, consistent levels of Calcium and Alk. Confused as to when, and how far apart I should be starting/stopping the dosing of each within each other. I always read about spreading out the dosing of Calcium and Alkalinity to avoid precipitate or Calcium Carbonate forming, at least I believe that's what I remember? What's a a safe amount of time? If I need to add 30 ml of Alk and 12.5 ml of Calcium I'd ideally like to spread them out over 5-10% increments though out the day unless a better regimen is recommended. I will be running either dosing pump/pumps off an Apex if that helps in terms of recommending either dosing pump I listed. Also, as far as the actual 2 part regimen I choose, I know that the Fluval won't be the way to go as I'd need a bottle of each every 8 days or so for Alk and 20 for Calcium. Should I just look for anything on BRS that has Calcium Chloride in the ingredients for Calcium and a similar ingredient list for Alkalinity that the Fluval Sea listed? I ask because it seems that each product seems to be working for my tank thus far. Thanks for any help you can offer and sticking through to the end of this long post!

 

[Randy Holmes-Farley]

While those additives may be fine, I'd generally avoid alkalinity supplements for a reef tank that have borate in them, since it is not significantly depleted by calcification.

The two ways to gauge dosing are:

1. Measure both calcium, and alkalinity frequently and dose both as needed (a huge amount of work in the long run).

2. Use a balanced system (two part (DIY or commercial), limewater/kalkwasser, CaCO3/CO2 reactor) and measure alkalinity occasionally to determine how much is needed. Calcium will follow along, as long as you water changes do not mess it up.

 

[dkeller_nc]

Given the system volume (52 gallons), the information that came with your supplements, 20 ppm of calcium per meq of alkalinity, and your consumption rate of 1.05 meq/L/day of alkalinity, I calculate that you would need to add 27 mL of your calcium supplement to balance your alkalinity additions:

20 x 1.05 = 21 ppm Ca needed, 5mL/20 gallon * 52 gallons = 13 mL/10ppm Ca

13 mL/10 ppm Ca * 21 ppm Ca = 27 mL of supplement

From the standpoint of dosing, many of us add the alkalinity/Ca required for a day's worth of consumption as a bolus (all at one time) dose, with a few minutes separating the Ca and Alk solution additions to prevent precipitation.

If you want to spread the amount added out over a few doses during the course of a day, I would suggest timing your pumps so that the Ca/Alk additions are about 2 minutes apart. If that's not possible with your particular pump (i.e., all heads run simultaneously), then I would simply place one output in your sump, and the other in the tank well away from the return pump outlet.

From the standpoint of switching to more cost-effective supplements, you need dry sodium bicarbonate, dry calcium carbonate and a magnesium mix. You can get all of these inexpensively as a kit from Bulk Reef Supply.

 

[ViktorVaughn]

While those additives may be fine, I'd generally avoid alkalinity supplements for a reef tank that have borate in them, since it is not significantly depleted by calcification.

The two ways to gauge dosing are:

1. Measure both calcium, and alkalinity frequently and dose both as needed (a huge amount of work in the long run).

2. Use a balanced system (two part (DIY or commercial), limewater/kalkwasser, CaCO3/CO2 reactor) and measure alkalinity occasionally to determine how much is needed. Calcium will follow along, as long as you water changes do not mess it up.

Thanks for the advice, I have already measured out my systems use via the method you described in number 1 and it was indeed a pain for a bit. I decided, after 2 months of manually dosing daily at 3 different times, that I definitely want to get onto a balanced system you described in number 2, most likely a two part dosing pump and commercial 2 part from Bulk Reef Supply.

Given the system volume (52 gallons), the information that came with your supplements, 20 ppm of calcium per meq of alkalinity, and your consumption rate of 1.05 meq/L/day of alkalinity, I calculate that you would need to add 27 mL of your calcium supplement to balance your alkalinity additions:

20 x 1.05 = 21 ppm Ca needed, 5mL/20 gallon * 52 gallons = 13 mL/10ppm Ca

13 mL/10 ppm Ca * 21 ppm Ca = 27 mL of supplement

From the standpoint of dosing, many of us add the alkalinity/Ca required for a day's worth of consumption as a bolus (all at one time) dose, with a few minutes separating the Ca and Alk solution additions to prevent precipitation.

If you want to spread the amount added out over a few doses during the course of a day, I would suggest timing your pumps so that the Ca/Alk additions are about 2 minutes apart. If that's not possible with your particular pump (i.e., all heads run simultaneously), then I would simply place one output in your sump, and the other in the tank well away from the return pump outlet.

From the standpoint of switching to more cost-effective supplements, you need dry sodium bicarbonate, dry calcium carbonate and a magnesium mix. You can get all of these inexpensively as a kit from Bulk Reef Supply.

Appreciate you taking the time running the numbers, those were the same figures I came up with, always nice to get independent confirmation. I will definitely look into the dry mixes from Bulk Reef Supply and than I guess just try and narrow down my dosing pump I choose to use. As far as I know, each pump that I am looking at purchasing has the ability to run each head independently so timing than to dose at different times shouldn't be an issue. I guess the BRS 1.1 ml/minute dosers definitely could since I would need one pump for each solution anyway and they would be standalone units. As for the Bubble Magus I am looking at, not too sure, I'll have to look into that more. Glad you brought that up, I wouldn't have thought to check

 

[dkeller_nc]

Appreciate you taking the time running the numbers, those were the same figures I came up with, always nice to get independent confirmation.

Well, based on your post above, it appears that you're adding about half as much calcium supplement (12.5 ml/day as opposed to 27 ml/day) as would be required to give you a 1:1 balance with your alkalinity supplement.

 

[ViktorVaughn]

The numbers as far as 27 ml of calcium equaling the amount of Alkalinity I currently dose. I do only dose the 12.5 ml a day, which is unbalanced and kind of spurred some of my initial inquiries. Not sure why my tank does not use Calcium and Alkalinity at a 1:1 ratio but it I have verified my uptake of each over a 3 day span quite a few times and found that the ratio is off, albeit in the same ratio every time.

 

[Randy Holmes-Farley]

IMO, the ratio gets skewed by water changes a huge amount, but isn't ever going to be off by a factor of two in the short term otherwise, unless the demand is so low that things like nitrate production are impacting alkalinity more than is calcification. Test kits are a lot more likely to be off than for the chemistry to be nonstandard. Recipes not being exactly comparable is another obvious reason.

Over 3 days? How much did calcium change over that time? Probably not much, which raises the uncertainty level a lot! Doubling the amount of calcium additive probably would be hardly noticeable with a test kit for anyone in 3 days.

This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

[ViktorVaughn]

IMO, the ratio gets skewed by water changes a huge amount, but isn't ever going to be off by a factor of two in the short term otherwise, unless the demand is so low that things like nitrate production are impacting alkalinity more than is calcification. Test kits are a lot more likely to be off than for the chemistry to be nonstandard. Recipes not being exactly comparable is another obvious reason.

Over 3 days? How much did calcium change over that time? Probably not much, which raises the uncertainty level a lot! Doubling the amount of calcium additive probably would be hardly noticeable with a test kit for anyone in 3 days.

This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

Thanks for the links to the great articles and all your help. Over three days, I saw a drop in Calcium of 25-30 ppm. Been a while and I dont have my logbook in front of me. I am finding post water changes that my calcium levels usually end up in the 460-470 range. I mix up 10 gallons of Instant Ocean Reef Crystals to 1.026 and change out the ~20% bi-weekly. Since the levels raise about 20 ppm over where I'd like to keep it, calcium dosing isn't required for 2-3 days while Alkakinity is still dosed daily. Not sure if the 2-3 days of Alkalinity dosing with no Calcium dosing would throw things off?

I have recently been contemplating switching salt mixes to something that when mixed at 1.026 will leave the Calcium, Alkalinity, and Magnesium where I keep my tank at. I found a cool thread on here a while back where the poster mixed up a bunch of different salt mixes and posted all the parameters. Are there any ill effects to switching salt after using the same brand for the 8 months the tanks been up?

 

[Randy Holmes-Farley]

There is nothing wrong with dosing no calcium for a while if calcium is as high or higher than you want.

The only thing to watch out for is whether stopping dosing is really useful. If the dosing would only have added 5 ppm per day and you wait until it drops 20 ppm, then need to add the equivalent of 4 days worth to get back to where you want, that isn't worth the trouble of stopping. That can happen because the daily drop in calcium is often hardly detectable with its while the alk drop often is easily detected.

There is nothing wrong with switching mixes as often as you want.

 

[mikieb]

This is happening to me as well, I just dose a little more alk than calc and it seems to work fine.

 

[mikieb]

IMO, the ratio gets skewed by water changes a huge amount, but isn't ever going to be off by a factor of two in the short term otherwise, unless the demand is so low that things like nitrate production are impacting alkalinity more than is calcification. Test kits are a lot more likely to be off than for the chemistry to be nonstandard. Recipes not being exactly comparable is another obvious reason.

Over 3 days? How much did calcium change over that time? Probably not much, which raises the uncertainty level a lot! Doubling the amount of calcium additive probably would be hardly noticeable with a test kit for anyone in 3 days.

This has more:

When Do Calcium and Alkalinity Demand Not Exactly Balance?
http://reefkeeping.com/issues/2004-12/rhf/index.htm

Great article btw thank you

 

[Randy Holmes-Farley]

Thanks. Mikieb.

Happy Reefing.

 

[deputydog95]

I have a question for you Randy.

My tank is SPS dominant and fairly heavily stocked. Typical Alk is 10dkh, Mg is 1350, and Ca is sub 350 using equal parts of my A&B solutions.

Everything I've read says that Alk and Ca are consumed in equal amounts, but after discussing my issue regarding getting my Ca up to appropriate levels for a SPS tank, my LFS said it's normal on their larger SPS systems to consume Ca at almost a 2 to 1 ratio to keep the numbers where they should be.

What are your thoughts on that?

 

[bertoni]

I think we discussed this in your other thread.

 

[deputydog95]

You did. Thank you.