Alkalinity dosing without Calcium

[RickvDam]

Hello!
My corals are really taking off which is noticeable in my parameters. After my waterchange I did some testing and my Alk had dropped to 7. (Used to be stable at 8).

I’m guessing it’s time to start dosing, but almost every Alk bottle I see comes with a calcium bottle. My calcium however is still stable at 440 like it always has been. Can I start with just dosing the Alk and wait with the calcium until that starts to drop?

 

[gbroadbridge]

Hello!
My corals are really taking off which is noticeable in my parameters. After my waterchange I did some testing and my Alk had dropped to 7. (Used to be stable at 8).

I’m guessing it’s time to start dosing, but almost every Alk bottle I see comes with a calcium bottle. My calcium however is still stable at 440 like it always has been. Can I start with just dosing the Alk and wait with the calcium until that starts to drop?

If your coral are consuming Alkalinity they are also consuming Calcium, however at a slower rate.
You can't see the calcium consumption as test kits do not have the resolution to show it.

You should dose a balanced amount of Alkalinity and Calcium - many two part dosing systems are balanced so that they maintain both levels by dosing based on Alkalinity consumption.

 

[RickvDam]

If your coral are consuming Alkalinity they are also consuming Calcium, however at a slower rate.
You can't see the calcium consumption as test kits do not have the resolution to show it.

You should dose a balanced amount of Alkalinity and Calcium - many two part dosing systems are balanced so that they maintain both levels by dosing based on Alkalinity consumption.

Alright thank you! Would it be an idea to look into switching salts instead of dosing? I currently use blue bucket, but for my Euphyllia tank I think reef crystals might be better. If everything goes right I will get a bigger tank in a few months, so then I won’t have to dose for a while.

 

[Randy Holmes-Farley]

Alright thank you! Would it be an idea to look into switching salts instead of dosing? I currently use blue bucket, but for my Euphyllia tank I think reef crystals might be better. If everything goes right I will get a bigger tank in a few months, so then I won’t have to dose for a while.

Dosing is always a cheaper way to maintain alkalinity and calcium.

 

[RickvDam]

Dosing is always a cheaper way to maintain alkalinity and calcium.

I suppose that’s true, but (I’m not entirely sure) if I start dosing now and upgrade from my 15G to a 60G tank in 2-3 months, the increased water volume with the same amount of corals might mean I won’t need to dose for a while. So, if I buy a dosing pump and supplements that I won’t need anymore in two months, wouldn’t it be more cost-efficient to just switch to a higher alkalinity salt mix? Both salts cost the same here.

 

[Randy Holmes-Farley]

I suppose that’s true, but (I’m not entirely sure) if I start dosing now and upgrade from my 15G to a 60G tank in 2-3 months, the increased water volume with the same amount of corals might mean I won’t need to dose for a while. So, if I buy a dosing pump and supplements that I won’t need anymore in two months, wouldn’t it be more cost-efficient to just switch to a higher alkalinity salt mix? Both salts cost the same here.

Water changes to maintain alk work in a low demand tank but not in a medium to high demand tank.

One suggestion is to buy the supplements now and dose them manually once a day, then see if you want a pump in the future.

 

[Reefahholic]

Give the tank only what it needs. If Ca
Consumption is absent, but there’s some KH consumption, only dose KH.

 

[Randy Holmes-Farley]

Give the tank only what it needs. If Ca
Consumption is absent, but there’s some KH consumption, only dose KH.

While that is of course true, most people mistakenly think they are in that situation because the calcium change (say, 7 ppm) is much slower to be detectable with typical calcium kits than is the balanced alk change (say, 1 dKH).

 

[Reefahholic]

While that is of course true, most people mistakenly think they are in that situation because the calcium change (say, 7 ppm) is much slower to be detectable with typical calcium kits than is the balanced alk change (say, 1 dKH).

I’ve seen tanks that consume much more KH than Ca. Dosing equal amounts in that situation only drives the Ca up out of target range and slows growth. I’ve seen it several times now. I used to try and dose equal amounts, and at times it seemed to work out, but other times it did not. I’ve had to change my position on this topic due to good data. Ca above 450-500 is not ideal for me.

I will say in most cases Ca consumption isn’t absent. It’s just much slower, and therefore shouldn’t be dosed equally.

 

[Randy Holmes-Farley]

I’ve seen tanks that consume much more KH than Ca. Dosing equal amounts in that situation only drives the Ca up out of target range and slows growth. I’ve seen it several times now. I used to try and dose equal amounts, and at times it seemed to work out, but other times it did not. I’ve had to change my position on this topic due to good data. Ca above 450-500 is not ideal for me.

I will say in most cases Ca consumption isn’t absent. It’s just much slower, and therefore shouldn’t be dosed equally

There are very few ways that alk is consumed without calcium, and the only significant ones are rising nitrate (50 ppm rise depletes 2.3 dKH), sulfur denitrators, or water changes with a low alk mix.

It is not true that tanks randomly can have significant alk consumption without calcium consumption in any other scenarios. The general rule that holds quite well is 2.8 dKH of alk is consumed for every 18-20 ppm of calcium and 0-2 ppm of magnesium.

 

[Reefahholic]

There are very few ways that alk is consumed without calcium

Ca is being consumed, it’s just much slower in some systems.

It is not true that tanks randomly can have significant alk consumption without calcium consumption in any other scenarios. The general rule that holds quite well is 2.8 dKH of alk is consumed for every 18-20 ppm of calcium and 0-2 ppm of magnesium.

I’ve seen significantly more alk consumption in many tanks compared to Ca consumption. That’s definitely been some systems that aren’t consuming anywhere near 18-20 ppm of Ca for every 2.8 dKH of alk. We tell them all to dose what the tank is consuming not what they heard on the forums. ICP’s or being corrected from 500-600+ back to 430.

It’s the same for trace elements. Although elements like nickel and zinc can be consumed at a rate that is very close, this is not always the case in every reef, and they should be dose off the actual demand vs trying to match the rate of consumption.

 

[bossman818]

I’m going through the exact same thing right now. I am only dosing Alkalinity though. As the corals start to grow they will consume calcium magnesium at a faster rate, that’s when you dose. Do not dose what is not needed.

 

[Randy Holmes-Farley]

Ca is being consumed, it’s just much slower in some systems.



I’ve seen significantly more alk consumption in many tanks compared to Ca consumption. That’s definitely been some systems that aren’t consuming anywhere near 18-20 ppm of Ca for every 2.8 dKH of alk. We tell them all to dose what the tank is consuming not what they heard on the forums. ICP’s or being corrected from 500-600+ back to 430.

It’s the same for trace elements. Although elements like nickel and zinc can be consumed at a rate that is very close, this is not always the case in every reef, and they should be dose off the actual demand vs trying to match the rate of consumption.

Well, I believe that folks making such observations are seeing testing issues. I do not believe what you are claiming is real, aside from the effects I noted, and there’s no processes that that I’ve heard of that can explain them.

 

[Randy Holmes-Farley]

I’m going through the exact same thing right now. I am only dosing Alkalinity though. As the corals start to grow they will consume calcium magnesium at a faster rate, that’s when you dose. Do not dose what is not needed.

No, that is just not true. ANY coral consumption MUST be 2.8 dKH per 18-20 ppm calcium.

 

[bossman818]

No, that is just not true. ANY coral consumption MUST be 2.8 dKH per 18-20 ppm calcium.

Been testing for 3 weeks straight. Alkalinity drops so I dose 2ml daily. Calcium stays consistent at 450 and magnesium at 1350. If I don’t dose alkalinity drops to 7 and other parameters are off. Maybe my tank is just weird lol

 

[Randy Holmes-Farley]

FWIW, I detail every significant process in reef tanks that impact alk (up and down) and not calcium (nothing consumes much calcium and not alk).

When Do Calcium and Alkalinity Demand Not Exactly Balance? by Randy Holmes-Farley

 

[bossman818]

Maybe what I am dosing has all and I never noticed. Seachem reef Carbonate? What do you think?

 

[Randy Holmes-Farley]

Been testing for 3 weeks straight. Alkalinity drops so I dose 2ml daily. Calcium stays consistent at 450 and magnesium at 1350. If I don’t dose alkalinity drops to 7 and other parameters are off. Maybe my tank is just weird lol

No, not weird, just a misinterpretation of what is happening.

What size tank?

Is nitrate changing or being dosed?

Any water changes during the time?

 

[Randy Holmes-Farley]

Maybe what I am dosing has all and I never noticed. Seachem reef Carbonate? What do you think?

That product is alk only.

 

[bossman818]

It’s a 80 gallon. I am dosing nothing but Seachem reef Carbonate. No water changes for a month. I don’t dose calcium, magnesium at all. Nitrate levels are consistent at 10. If I don’t dose the 2ML daily alkalinity drops.