Is AFR just calcium?

BriDroid · Sep 5, 2025

I agree with everyone here, there is no way that your Mg is 1100ppm if you’re dosing AFR and doing regular water changes. It takes some blind faith sometimes to trust the process, it did for me!

exnisstech · Sep 5, 2025

Ballyhoo I'm just posting this to show an example of a tank that has been on AFR for a couple of years following most of the advice given above.
I test alk on a regular basis. I'm currently testing daily because I made some changes to increase my pH and coral are growing so consumption is increasing fairly quickly. I've have never tested magnesium. I test calcium once every 4-6 weeks but mine hasn't been trending up so my small WCs I do to vacuum detritus must be enough to keep it in check. AFR has been very simple but effective for me and I love simple. I use a reefdose 2 but did manually dose once a day for 9 months.
Corals were all grown from small frags.
Currently dosing 45ml AFR daily up from 30ml 3 weeks ago when I increased the pH. Tank is approx 65g

Then.

Now

Randy Holmes-Farley · Sep 5, 2025

Ballyhoo said:
it got low though. i had unpredictable coral issues until I used my Salifert mg test kit and started dosing 1.5 mg a day. my CA though was up to 490. so something is using mg. i'm dosing every day 13 mg of AFR and calcium is like 460. So I don't feel like I have a lot of room to dose above 14 mg of AFR. My KH is down to about 6.7 without dosing alkalinity. I mean, I can't argue with the numbers of the tests. I bought several salifert kits just to make sure that one wasn't bad. The numbers are consistent. so again if I just dose 14 mg of AFR every day, my calcium would be about 460, alkalinity would be about 6.7 and magnesium probably would be down 11 or 1200. So what's the situation here? I don't understand I'm supposed to just increase my AFR to get calcium above 500?

Just a few quick comments.

You are saying mg (not mL) dosed in most posts. Is the really what you mean? Are you weighing and dosing it dry or something?

Have you ever tried your calcium and magnesium kits on your new salt water?

twentyleagues · Sep 5, 2025

Randy Holmes-Farley said:
You are saying mg (not mL) dosed in most posts. Is the really what you mean? Are you weighing and dosing it dry or something?

Have you ever tried your calcium and magnesium kits on your new salt water?

I was wondering this as well.

rishma · Sep 5, 2025

I assumed mg was a typo and he meant mL because 14ml is a reasonable AFR dose for his tank size.

Ballyhoo · Sep 5, 2025

ML, sorry. lol.

so with all the recommendations above clearly my 14 ML of AFR is not sufficient as there above is a 65 gallon system dosing 45 ml of AFR. maybe my number should be closer to 25 or 30 ML AFR. Is it recommended to gradually dose up incrementally, or is it okay maybe to add 5 mL a day like go today from 14 to 19 ml of AFR And then maybe tomorrow 25 and test again and then maybe 30 until my ALK gets to 8.0. Or should I make smaller incremental increases in the AFR dosage?

thanks again!!

also, would love to know why some here are having multiple doser pumps?What are you dosing with four pumps for example?

exnisstech · Sep 5, 2025

Ballyhoo said:
ML, sorry. lol.

so with all the recommendations above clearly my 14 ML of AFR is not sufficient as there above is a 65 gallon system dosing 45 ml of AFR. maybe my number should be closer to 25 or 30 ML AFR. Is it recommended to gradually dose up incrementally, or is it okay maybe to add 5 mL a day like go today from 14 to 19 ml of AFR And then maybe tomorrow 25 and test again and then maybe 30 until my ALK gets to 8.0. Or should I make smaller incremental increases in the AFR dosage?

thanks again!!

also, would love to know why some here are having multiple doser pumps?What are you dosing with four pumps for example?

The amount of AFR needed is strictly related to the type and amount of coral being kept and the alk consumption rate not water volume.

Randy Holmes-Farley · Sep 5, 2025

Ballyhoo said:
ML, sorry. lol.

so with all the recommendations above clearly my 14 ML of AFR is not sufficient as there above is a 65 gallon system dosing 45 ml of AFR. maybe my number should be closer to 25 or 30 ML AFR. Is it recommended to gradually dose up incrementally, or is it okay maybe to add 5 mL a day like go today from 14 to 19 ml of AFR And then maybe tomorrow 25 and test again and then maybe 30 until my ALK gets to 8.0. Or should I make smaller incremental increases in the AFR dosage?

thanks again!!

also, would love to know why some here are having multiple doser pumps?What are you dosing with four pumps for example?

I use one doser for AFR, two for my AWC, one for phyto, one for ammonium bicarbonate.

rishma · Sep 5, 2025

Ballyhoo said:
ML, sorry. lol.

so with all the recommendations above clearly my 14 ML of AFR is not sufficient as there above is a 65 gallon system dosing 45 ml of AFR. maybe my number should be closer to 25 or 30 ML AFR. Is it recommended to gradually dose up incrementally, or is it okay maybe to add 5 mL a day like go today from 14 to 19 ml of AFR And then maybe tomorrow 25 and test again and then maybe 30 until my ALK gets to 8.0. Or should I make smaller incremental increases in the AFR dosage?

thanks again!!

also, would love to know why some here are having multiple doser pumps?What are you dosing with four pumps for example?

you want to match your AFR dose to your alkalinity consumption. It will be different for every tank.

Since you indicated your alkalinity is 6.7 and your target is 8, you can dose enough reach 8 and adjust from there. About 42ml will increase your tank from 6.7 to 8, not counting for consumption. Assume it takes about 24hrs for the alkalinity to show up in the tank.

If it was my tank I would dose 45 ml today in the early part of the lighting cycle. I’d test again tomorrow and dose 16ml per day (about 0.5 dKH dose) for a few days and test again. If your alkalinity is falling then increase the dose a little and repeat the process until stable. I don’t suggest testing more than once every few days because small changes in alkalinity are hard to detect if testing too frequently.

Ballyhoo · Sep 5, 2025

Randy Holmes-Farley said:
I use one doser for AFR, two for my AWC, one for phyto, one for ammonium bicarbonate.

wow dosing phyto. I haven't heard of that. Of course I don't know your system and I don't know what other supplements you're adding for like Reefroid etc. I thought I saw one of your other posts you've gone mostly to Nems? Or maybe I'm incorrect.

Troylee · Sep 5, 2025

Ballyhoo said:
it got low though. i had unpredictable coral issues until I used my Salifert mg test kit and started dosing 1.5 mg a day. my CA though was up to 490. so something is using mg. i'm dosing every day 13 mg of AFR and calcium is like 460. So I don't feel like I have a lot of room to dose above 14 mg of AFR. My KH is down to about 6.7 without dosing alkalinity. I mean, I can't argue with the numbers of the tests. I bought several salifert kits just to make sure that one wasn't bad. The numbers are consistent. so again if I just dose 14 mg of AFR every day, my calcium would be about 460, alkalinity would be about 6.7 and magnesium probably would be down 11 or 1200. So what's the situation here? I don't understand I'm supposed to just increase my AFR to get calcium above 500?

Low mag doesn’t kill corals.. I highly doubt this thing tests correctly either.. I haven’t dosed mag in a long time but you can see mines always near 1100 so it says.. yesterday I did a 30% water change and it dropped my mag 50 points with a salt mix that tests 1400 on the label. lol..

Troylee · Sep 5, 2025

While I got you here @Randy Holmes-Farley is this a testing error on tridents part or is there some kind of ion balance with mag and calcium? Every trident does this trend when mag rises cal will drop and vice versa is cal rises then mag drops? I did a water change yesterday anbout 30% and you can see my calcium went up 50 points and my mag dropped 50 points.. you can see the trend in the graphs.

BriDroid · Sep 5, 2025

rishma said:
you want to match your AFR dose to your alkalinity consumption. It will be different for every tank.

Since you indicated your alkalinity is 6.7 and your target is 8, you can dose enough reach 8 and adjust from there. About 42ml will increase your tank from 6.7 to 8, not counting for consumption. Assume it takes about 24hrs for the alkalinity to show up in the tank.

If it was my tank I would dose 45 ml today in the early part of the lighting cycle. I’d test again tomorrow and dose 16ml per day (about 0.5 dKH dose) for a few days and test again. If your alkalinity is falling then increase the dose a little and repeat the process until stable. I don’t suggest testing more than once every few days because small changes in alkalinity are hard to detect if testing too frequently.

Once you “pick” a dose, I find it a little less complicated if you test alkalinity every 2 or 3 days and the react by adjusting the AFR dose. Testing and adjusting everyday can feel a bit like chasing your tail at first!

rishma · Sep 5, 2025

BriDroid said:
rishma said:

you want to match your AFR dose to your alkalinity consumption. It will be different for every tank.

Since you indicated your alkalinity is 6.7 and your target is 8, you can dose enough reach 8 and adjust from there. About 42ml will increase your tank from 6.7 to 8, not counting for consumption. Assume it takes about 24hrs for the alkalinity to show up in the tank.

If it was my tank I would dose 45 ml today in the early part of the lighting cycle. I’d test again tomorrow and dose 16ml per day (about 0.5 dKH dose) for a few days and test again. If your alkalinity is falling then increase the dose a little and repeat the process until stable. I don’t suggest testing more than once every few days because small changes in alkalinity are hard to detect if testing too frequently.

Click to expand...

Once you “pick” a dose, I find it a little less complicated if you test alkalinity every 2 or 3 days and the react by adjusting the AFR dose. Testing and adjusting everyday can feel a bit like chasing your tail at first!

100% agree. Once I think I have it dialed in, I go to weekly tests or longer.

Randy Holmes-Farley · Sep 5, 2025

Ballyhoo said:
wow dosing phyto. I haven't heard of that. Of course I don't know your system and I don't know what other supplements you're adding for like Reefroid etc. I thought I saw one of your other posts you've gone mostly to Nems? Or maybe I'm incorrect.

The phyto is to feed pods that my mandarin consumes, for my sponges, and other filter feeders. :)

Randy Holmes-Farley · Sep 5, 2025

Troylee said:
While I got you here @Randy Holmes-Farley is this a testing error on tridents part or is there some kind of ion balance with mag and calcium? Every trident does this trend when mag rises cal will drop and vice versa is cal rises then mag drops? I did a water change yesterday anbout 30% and you can see my calcium went up 50 points and my mag dropped 50 points.. you can see the trend in the graphs.

How large of a water change? There’s no reason for them to move in different directions like that unless the new salt water causes it (or it’s test error).

gbroadbridge · Sep 5, 2025

Ballyhoo said:
also, would love to know why some here are having multiple doser pumps?What are you dosing with four pumps for example?

The are a few different ways to dose for coral consumption.
On my Nano tank I use AFR with a single head doser.

My 90gal tank uses 3 part dosing which uses three dosing heads to dose separate components - it is simply cheaper for a large heavy consumption system, but more complex.

I use another dosing head occasionally on the large tank to dose supplemental Nitrate.

Every tank is different.

Troylee · Sep 5, 2025

Randy Holmes-Farley said:
How large of a water change? There’s no reason for them to move in different directions like that unless the new salt water causes it (or it’s test error).

30% water change with reef crystals.. I’m just curious either way let’s say I didn’t change water.. if I dose my calcium today let’s say 20 points on purpose my trident will drop the mag 20 points.. is there some kind of ion balance there or is it’s just testing errors on both parts with the trident? I’ve seen this over and over with tridents not just mine that if you raise calcium or mag the opposite drops like clock work.