All for Reef Dosing Calculation Help

[Hans-Werner]

The stability of saltwater oversaturated with calcium carbonate depends from many factors, phosphate concentration and organic compounds amongst others. This is the reason why freshly prepared saltwater is so much more prone to the formation of precipitates. You can split a batch of freshly prepared saltwater in two and put the one halft into a cycled tank and the other half in a sterile tank and you will get precipitates only in the sterile tank.

The role of phosphates can be seen clearly when phosphate concentration gets locally or generally reduced. In local reduction by bacterial activity, promoted by organic carbon dosing, i. e. the bottom gravel may clump or even solidify from calcium carbonate precipitates.

Sinking alkalinity after phosphate removal may not be a sign of increased coral growth but only of increased precipitation. If this is the case it makes no sense to counteract it with increased dosing.

So it is hard to give recommendations for a tank at the limit of calcium carbonate saturation. I recommend trial and improvement. You seem very skilled to me and I am quite sure you will find a good solution.

 

[arking_mark]

The stability of saltwater oversaturated with calcium carbonate depends from many factors, phosphate concentration and organic compounds amongst others. This is the reason why freshly prepared saltwater is so much more prone to the formation of precipitates. You can split a batch of freshly prepared saltwater in two and put the one halft into a cycled tank and the other half in a sterile tank and you will get precipitates only in the sterile tank.

The role of phosphates can be seen clearly when phosphate concentration gets locally or generally reduced. In local reduction by bacterial activity, promoted by organic carbon dosing, i. e. the bottom gravel may clump or even solidify from calcium carbonate precipitates.

Sinking alkalinity after phosphate removal may not be a sign of increased coral growth but only of increased precipitation. If this is the case it makes no sense to counteract it with increased dosing.

So it is hard to give recommendations for a tank at the limit of calcium carbonate saturation. I recommend trial and improvement. You seem very skilled to me and I am quite sure you will find a good solution.

Very interesting. My phosphates have never been above 0.09ppm and typically closer to just above 0.

I am seeing clumping sand.

I'm not seeing coraline algae even though I brought 2 rocks over from my old tank that are covered in it.

I could switch over to a 2-part dosing and see if that could stabilize my tank. Or just see where the tank goes on current dosing, maybe it will settle somewhere. Or stop dosing altogether and see where it goes to. However, I am wondering if I need to adjust my fixed pH if I let the tank Alk continue to fall.

 

[Hans-Werner]

I think a fixed pH could be a good idea. However, I see no necessity to keep it above 8.1 or maybe even 8.0. I think a fixed pH means you do not let it drop below this pH, but at the high end there is no limit. Is this correct?

So I would avoid pHs under 8.1 at night and let the assimilation of the corals do the job to increase pH during the day. What do you think about this?

 

[arking_mark]

A couple of other thoughts as I read through threads and articles.

I think a fixed pH could be a good idea. However, I see no necessity to keep it above 8.1 or maybe even 8.0. I think a fixed pH means you do not let it drop below this pH, but at the high end there is no limit. Is this correct?

So I would avoid pHs under 8.1 at night and let the assimilation of the corals do the job to increase pH during the day. What do you think about this?

The "natural" pH for my tank is 7.9ish with my higher CO2 house air. Maximum it hits is 8. With just Kalkwasser drip, it would max out around 8.1ish. So if I set my pH to anything above 8.1, it will lock in at that number.

 

[Hans-Werner]

I am seeing clumping sand.

... most likely caused by high pH from Kalkwasser dosing causing precipitation.

 

[arking_mark]

... most likely caused by high pH from Kalkwasser dosing causing precipitation.

I don't think the clumping sand is a big issue. I've been breaking it up. However, it probably accounts for a good bit of my Alk consumption.

I'm thinking that I need to up my organics a little to season the rock and sand and "poison" those surfaces with phosphate and Mag.

 

[arking_mark]

I'll wait to hear @Randy Holmes-Farley thoughts, but I think for now I'll:
1. Increase organic input through feeding
2. Continue to monitor Alk
3. If Alk continues to fall to say 7.4ish, dose 1ml of AFR and see how the tank reacts

 

[Hans-Werner]

I don't think the clumping sand is a big issue. I've been breaking it up. However, it probably accounts for a good bit of my Alk consumption.

I agree. But it is an indicator. And a place were some of you Alk goes.

 

[arking_mark]

On a positive note, I feel like I'm very close to tank parameter stability. So far, I've avoided (knock on wood) any algae or other issues in display tank. I was sort of expecting an ugly phase by now.

I just hope that focusing on stability will allow me to keep some more SPS. I've had very little luck so far with the exception of a couple corals brought over from my old tank.

I've been slowly dialing in my tank nutrition, trying to optimize flow, and very very slowly adjusting my lights. Part of me feels like the parameters while not "locked in" are very normal in their ebb and flow and that nutrition, flow, and light may be the issue.

As I only like to change one thing at a time in the tank, I've been focusing on parameter stability.

Maybe I need a little more biodiversity and should add some additional bacteria. Maybe carbon dosing will have feed the tank better. But those are tweaks for later if my corals still aren't successful.

 

[Randy Holmes-Farley]

@Randy Holmes-Farley If I understand your articles on pH/Ca/Alk/Mag in the saltwater aquarium. With pH, Alk, and air CO2, given any 2 of these numbers, I should be able to calculate the 3rd. So with a fixed pH of 8.3 and a dKH of 7.8 my air CO2 should be very close to 350. (I couldn't find your equation and just eyeballed your graph). Recall that I basically maintain my pH via CO2 scrubber and can drive H out. Hence why I would like to stabilize near these numbers.

If you know any two of alkalinity , pH, and CO2 in the water, you can calculate the third. Knowing CO2 in the air is not needed or adequate, as it doesn't always reflect CO2 in the water.

Some abiotic precipitation is normal in a reef tank, but if you want to reduce it's magnitude, this is a copy and paste of my usual recommendations:

Sand hardening happens initially when the tank is set up then slows as the sand becomes covered in organics, magnesium, and phosphate, but here is my standard recommendation to reduce precipitation on sand, heaters, pumps, etc:

1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

 

[arking_mark]

If you know any two of alkalinity , pH, and CO2 in the water, you can calculate the third. Knowing CO2 in the air is not needed or adequate, as it doesn't always reflect CO2 in the water.

Some abiotic precipitation is normal in a reef tank, but if you want to reduce it's magnitude, this is a copy and paste of my usual recommendations:

Sand hardening happens initially when the tank is set up then slows as the sand becomes covered in organics, magnesium, and phosphate, but here is my standard recommendation to reduce precipitation on sand, heaters, pumps, etc:

1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

Yeah, read this on 2 other threads. I don't think I want to swing parameters to reduce abiotic precipitation. Maybe minor changes to slow it a little. I'd rather just get the parameters stable and let the tank find its balance.

With regard to 1-5 above...
1. pH is stable and I'd like to keep it that way. I may drop it a little more.
2. I'm trying to stabilize Alk and it's declining with dosing. So I don't want to stop dosing. Maybe let it drop further and see if it stabilizes somewhere lower?
3. This I think I will do. If Alk continues to drop, I'll start to re-dose AFR at a much lower dosage to see how the tank responds. Then slowly increase it and maybe replace some of my Kalk dosings.
4. My Mag is normal to high
5. I'm going to up my feeding and start carbon doing once the Alk is stabilized to see if there is benefit from carbon.

 

[arking_mark]

Thank you @Hans-Werner and @Randy Holmes-Farley

Fantastic feedback in helping me with my 1st world reef tank problems and coming up with a plan.

 

[arking_mark]

If you know any two of alkalinity , pH, and CO2 in the water, you can calculate the third. Knowing CO2 in the air is not needed or adequate, as it doesn't always reflect CO2 in the water.

Some abiotic precipitation is normal in a reef tank, but if you want to reduce it's magnitude, this is a copy and paste of my usual recommendations:

Sand hardening happens initially when the tank is set up then slows as the sand becomes covered in organics, magnesium, and phosphate, but here is my standard recommendation to reduce precipitation on sand, heaters, pumps, etc:

1. Stop all efforts to boost pH.
2. Stop dosing alk for a bit and let it decline.
3. Reduce pH by switching to a low pH alk mix like sodium bicarbonate, or a calcium organic such as Tropic Marin All for Reef.
4. Ensure magnesium is normal to high.
5. Keep organics and phosphate on the high side.

After a few days of not dosing alk, restart slowly, adding additives to a very high flow area so it mixes in fast.

@Randy Holmes-Farley One more question on #5 if you don't mind.

NO3/PO4 is in my target range (NO3 1-5ppm, PO4 0.01-0.09). I have increased feeding as these numbers have been closer to the bottom of that range.

Would starting carbon dosing help with upping organics? (I'd be using TM Reef Actif which is not supposed to impact NO3/PO4 and "contains marine biopolymers".)

I know: "Do not believe manufacturer or LFS claims without doing your homework"

 

[Randy Holmes-Farley]

@Randy Holmes-Farley One more question on #5 if you don't mind.

NO3/PO4 is in my target range (NO3 1-5ppm, PO4 0.01-0.09). I have increased feeding as these numbers have been closer to the bottom of that range.

Would starting carbon dosing help with upping organics? (I'd be using TM Reef Actif which is not supposed to impact NO3/PO4 and "contains marine biopolymers".)

I know: "Do not believe manufacturer or LFS claims without doing your homework"

It is not evident to me that dosing the typical small molecule organics we use (ethanol/acetic acid, etc.) will up the types of organics that get onto calcium carbonate surfaces to inhibit precipitation (usually bigger anionic molecules such as certain proteins and polysaccharides).

Hans Werner can give a better answer on the Reef Actif since I'm not certain of the exact composition. But it may be helpful in that context.

 

[arking_mark]

It is not evident to me that dosing the typical small molecule organics we use (ethanol/acetic acid, etc.) will up the types of organics that get onto calcium carbonate surfaces to inhibit precipitation (usually bigger anionic molecules such as certain proteins and polysaccharides).

Hans Werner can give a better answer on the Reef Actif since I'm not certain of the exact composition. But it may be helpful in that context.

So is heavy feeding a good way to do this? Or are there other techniques?

 

[Randy Holmes-Farley]

So is heavy feeding a good way to do this? Or are there other techniques?

heavy feeding will increase organics, as does less GAC and skimming.

 

[arking_mark]

heavy feeding will increase organics, as does less GAC and skimming.

Awesome. Thanks.

 

[arking_mark]

So some interesting findings. Dosing AFR in my tank definitely doesn't behave as expected.

After 4 days of steady ~0.2dKH drops, I add 1ml of AFR to my 400l tank. 12hrs after dose tank dKH continued to drop. I added a 2nd 1ml AFR dose. 12hrs later dKH was back where I started when I 1st started dosing it.

So after 24hr tank was at same dKH! Great 1ml every 12hrs seemed like a good start. So I dosed another 1ml...however, tank Alk then continued to rise all the way to 8dKH, but is now dropping again.

I still think this 1ml dose every 12hrs might be my tanks starting point. So I'll continue to dose and see what happens.