Dosing two part advice

[ID-Reefer]

Im hoping you chemistry pros and advanced reefers out there can offer some advice. 250 gal. system has been up and running for about 15 months. Ive had decent success but will occasionally lose a coral. A torch will bail or an Acro will start to slowly (very slowly) die off. But for the most part the tank is running very well. Id like to get things more dialed in if possible as I still think something could be off.

Parameters
salinity: 1.025
dKH: 8.6 (Hanna)
Calcium: 407 (Apex Trident recently calibrated)
Magnesium: 1331 (Apex Trident recently calibrated)
PH range: 8.26-8.45 (Apex probe)
N03: 11.7 (Hanna)
P04: .06 (Hanna)
All water is RODI with 0 TDS
Good flow & have measured PAR. Skim 24/7 using outside air supply.

Salt :
I use Red Sea coral pro salt. Auto water change of 3 gallons/day. Note the Alkalinity of the salt is considerably higher at 11.5-1.25 dKH. But since it is an every day auto water change in small amounts during a 24hr period my assumption the salt not matching my target is not a problem as there are no large fluctuations in a 250 gal. system.


Daily Dosing:
I use the BRS (Randy's) two part.
Magnesium manually in the morning - 16% of amount of soda ash used = 17ml.
Alk (Soda Ash) Auto dosing Apex DOS - 110 ml.
Calcium (Calcium Chloride) Auto dosing Apex DOS 100 ml.

A month ago my P04 was creeping up to .16 and N03 to 15.5. Not crazy high but I started manually dosing a small amount of NOPOX (6ml and now maintaining current levels at 4ml of NOPOX). as I wanted to go very slow.

Questions:
1. It is my understanding that I should be dosing equal amounts for Alk and calcium but since my salt has higher alkalinity that it wouldn't be 1:1 and I should dose based on testing of each (which is what ive been doing)?

2. I recently read a few people suggest that if using this 2 part system that Alk should be kept lower in the 7.5-8 range. Id like to have that confirmed by someone before slowly dropping my alk however - as I haven't seen Randy suggest that.

3. Ive gotten into the habit of looking at my APEX alk level daily and adjusting my dosing every other day just by 5-10 ml. as needed to stay in that 8.5 range. Then double checking with Hanna once a week to make sure APEX Trident is staying accurate. Is this common practice? Do most tanks need to have alk dosing adjusted this this frequently to stay within a small range of .5?

Appreciate the help/feedback.

 

[Huskereef]

Im hoping you chemistry pros and advanced reefers out there can offer some advice. 250 gal. system has been up and running for about 15 months. Ive had decent success but will occasionally lose a coral. A torch will bail or an Acro will start to slowly (very slowly) die off. But for the most part the tank is running very well. Id like to get things more dialed in if possible as I still think something could be off.

Parameters
salinity: 1.025
dKH: 8.6 (Hanna)
Calcium: 407 (Apex Trident recently calibrated)
Magnesium: 1331 (Apex Trident recently calibrated)
PH range: 8.26-8.45 (Apex probe)
N03: 11.7 (Hanna)
P04: .06 (Hanna)
All water is RODI with 0 TDS
Good flow & have measured PAR. Skim 24/7 using outside air supply.

Salt :
I use Red Sea coral pro salt. Auto water change of 3 gallons/day. Note the Alkalinity of the salt is considerably higher at 11.5-1.25 dKH. But since it is an every day auto water change in small amounts during a 24hr period my assumption the salt not matching my target is not a problem as there are no large fluctuations in a 250 gal. system.


Daily Dosing:
I use the BRS (Randy's) two part.
Magnesium manually in the morning - 16% of amount of soda ash used = 17ml.
Alk (Soda Ash) Auto dosing Apex DOS - 110 ml.
Calcium (Calcium Chloride) Auto dosing Apex DOS 100 ml.

A month ago my P04 was creeping up to .16 and N03 to 15.5. Not crazy high but I started manually dosing a small amount of NOPOX (6ml and now maintaining current levels at 4ml of NOPOX). as I wanted to go very slow.

Questions:
1. It is my understanding that I should be dosing equal amounts for Alk and calcium but since my salt has higher alkalinity that it wouldn't be 1:1 and I should dose based on testing of each (which is what ive been doing)?

2. I recently read a few people suggest that if using this 2 part system that Alk should be kept lower in the 7.5-8 range. Id like to have that confirmed by someone before slowly dropping my alk however - as I haven't seen Randy suggest that.

3. Ive gotten into the habit of looking at my APEX alk level daily and adjusting my dosing every other day just by 5-10 ml. as needed to stay in that 8.5 range. Then double checking with Hanna once a week to make sure APEX Trident is staying accurate. Is this common practice? Do most tanks need to have alk dosing adjusted this this frequently to stay within a small range of .5?

Appreciate the help/feedback.

following. I'm in the process of setting up my Apex DOS for 2 part currently, on a new system.

 

[Randy Holmes-Farley]

I'd stick to dosing 1:1, unless calcium is actually already bordering too high or too low. It may seem counter-intuitive, but relative to NSW, Red Sea coral pro is actually an excess calcium mix, not an excess alk mix.

If you take Red Sea Coral pro at 465 ppm calcium and 12 dKH, and remove calcium carbonate to 420 ppm calcium (35 ppt), you get down to 5.4 dKH.

 

[Randy Holmes-Farley]

Im hoping you chemistry pros and advanced reefers out there can offer some advice. 250 gal. system has been up and running for about 15 months. Ive had decent success but will occasionally lose a coral. A torch will bail or an Acro will start to slowly (very slowly) die off. But for the most part the tank is running very well. Id like to get things more dialed in if possible as I still think something could be off.

Parameters
salinity: 1.025
dKH: 8.6 (Hanna)
Calcium: 407 (Apex Trident recently calibrated)
Magnesium: 1331 (Apex Trident recently calibrated)
PH range: 8.26-8.45 (Apex probe)
N03: 11.7 (Hanna)
P04: .06 (Hanna)
All water is RODI with 0 TDS
Good flow & have measured PAR. Skim 24/7 using outside air supply.



2. I recently read a few people suggest that if using this 2 part system that Alk should be kept lower in the 7.5-8 range. Id like to have that confirmed by someone before slowly dropping my alk however - as I haven't seen Randy suggest that.

Alk can be kept anywhere in the 7-11 dKH range (IMO), but at the higher alk end (where hard corals calcify faster) you need to ensure you have adequate N and P to avoid burnt tips, possibly from skeletons growing faster than tissue can keep up.

 

[Randy Holmes-Farley]

3. Ive gotten into the habit of looking at my APEX alk level daily and adjusting my dosing every other day just by 5-10 ml. as needed to stay in that 8.5 range. Then double checking with Hanna once a week to make sure APEX Trident is staying accurate. Is this common practice? Do most tanks need to have alk dosing adjusted this this frequently to stay within a small range of .5?

You mean the dosing needed is uneven? How much does 5-10 ml mean in dKH?

 

[ID-Reefer]

You mean the dosing needed is uneven? How much does 5-10 ml mean in dKH?

I have never dosed the same amount. Right now its about 110 ml soda ash and 100 ml calcium chloride. I am not sure how much difference 5-10 ml would make a exactly - I see a trend of it slowly dropping or going up and adjust by 5 ml. increments to offset the direction and try to keep it steady.

You are suggesting I dose 1:1 unless my calcium gets to high. What in your opinion is the max the calcium should be?

Thanks!

 

[Randy Holmes-Farley]

I have never dosed the same amount. Right now its about 110 ml soda ash and 100 ml calcium chloride. I am not sure how much difference 5-10 ml would make a exactly - I see a trend of it slowly dropping or going up and adjust by 5 ml. increments to offset the direction and try to keep it steady.

You are suggesting I dose 1:1 unless my calcium gets to high. What in your opinion is the max the calcium should be?

Thanks!

If calcium is 400 ppm or less, I'd raise the calcium dose. If it is 500 ppm or more, I'd reduce it.

100:110 is quite close and is certainly reasonable. Water changes and other processes can easily cause that.

 

[thatmanMIKEson]

If calcium is 400 ppm or less, I'd raise the calcium dose. If it is 500 ppm or more, I'd reduce it.

100:110 is quite close and is certainly reasonable. Water changes and other processes can easily cause that.

If its a diy 2 part mix, could also the potency/accuracy of the mixture make it seem to need an unbalanced ratio of 2 part additives?

 

[Randy Holmes-Farley]

If its a diy 2 part mix, could also the potency/accuracy of the mixture make it seem to need an unbalanced ratio of 2 part additives?

If you mixed it wrong, certainly. 10% is within the noise of testing and such, but some folks claim 2:1 and things like that, which is not from the mix not matching calcification demand.

Also, the amount of magnesium incorporation and hence the amount of calcium consumption varies a bit tank to tank as some organisms (like coralline) use more magnesium and less calcium than many corals.