Another dosing help thread..

[rishma]

Well that’s been my hands on experience.. I just bumped my alk up from 7 to 9.5 and my ph didn’t really change.. my alk usage went way up and it’s a lot more to maintain but I didn’t really see a difference in my ph. Maybe .1 or .2 at the very most! It wouldn’t be recognizable in terms of growth from a ph standpoint.

0.1 or 0.2 is pretty significant in pH

 

[rishma]

Fair enough. I respect it. Makes sense.

I have a slightly different opinion.

Assuming the goal of higher pH is for elevated growth

In my experience, alk is perfectly fine up to 11 dKH. I think there’s a lot of fear mongering with higher alk, but let’s put that aside for now.

High alk will lead to a higher pH after equilibrium with CO2. Not so drastic, but has some effect.

The exact tank running 10dKH will consume more alk than the same tank at 7 dKH. Both from abiotic and biotic precipitation.

If using high pH additives (like hydroxide or carbonate,) the higher alk demand can have a compounded effect on the additive’s pH boost, simply because more will need to be dosed.


A few criteria needs to be met: needs to use carbonate or hydroxide for alk and also needs to have a decent alkalinity demand.

Bare tanks using all for reef or bicarbonate for the alk won’t get any pH benefit, even if raising the alk. But raising the alk can still have some positive effect on growth for many corals, even if the pH is lower.


Do most people need to do this? Heck nah. A tank can be very happy with pH as low as 7.8.



But for people like me who gets a rush from competing in grow-out contests? It’s what gives me an edge over my competitors.

In the old days I ran 10-12 dKH but who knew what my phosphate was

 

[Miami Reef]

0.1 or 0.2 is pretty significant in pH

Facts. lol

 

[Troylee]

0.1 or 0.2 is pretty significant in pH

Is it? I don’t feel like it is! I’m still scratching my head if the higher temps my tank runs is worth the .1 ph I get from pulling the Vegas 110° weather lol.. my tank runs 80-83 because of that! It would be in the high 70’s if I pull the skimmer line back inside.

 

[rishma]

0.1 or 0.2 is pretty significant in pH

Is it? I don’t feel like it is! I’m still scratching my head if the higher temps my tank runs is worth the .1 ph I get from pulling the Vegas 110° weather lol.. my tank runs 80-83 because of that! It would be in the high 70’s if I pull the skimmer line back inside.

Others can probably explain it better than me, but pH is a log scale so 0.1 is something like 25% change in acidity

 

[Randy Holmes-Farley]

But for people like me who gets a rush from competing in grow-out contests? It’s what gives me an edge over my competitors.

Yes, I can see pulling out all the stops in a grow out competition.

In your experience and those of others in such competitions, how do you perceive nitrate and phosphate levels impacting growth?

 

[Troylee]

Yes, I can see pulling out all the stops in a grow out competition.

In your experience and those of others in such competitions, how do you perceive nitrate and phosphate levels impacting growth?

Don’t know I never really tested them till the other day lol.. n03 is fine my p04 is through the roof! but the corals are happy so hey! Haha that’s .3 for people who don’t wanna do the math.

 

[Troylee]

Others can probably explain it better than me, but pH is a log scale so 0.1 is something like 25% change in acidity

Yeah I suck at chemistry.. that’s Randy’s job! I just know what numbers are good and how to achieve them so that’s how I roll!

 

[Miami Reef]

Yes, I can see pulling out all the stops in a grow out competition.

In your experience and those of others in such competitions, how do you perceive nitrate and phosphate levels impacting growth?

I’m always experimenting.

The average nitrate was about 4-6 ppm NO3
The average phosphate was about 0.07 ppm.

I won the last contest. Not sure if you heard about it, but I couldn’t have been happier!

^ one year of growth.



This contest I’m switching to a different approach with my nutrients by keeping them much higher. The competition is very strong this round.

 

[Randy Holmes-Farley]

I’m always experimenting.

The average nitrate was about 4-6 ppm NO3
The average phosphate was about 0.07 ppm.

I won the last contest. Not sure if you heard about it, but I couldn’t have been happier!

^ one year of growth.



This contest I’m switching to a different approach with my nutrients by keeping them much higher. The competition is very strong this round.

Congrats! I’ll be interested to see how higher nutrients do. :)

 

[rishma]

Is it? I don’t feel like it is! I’m still scratching my head if the higher temps my tank runs is worth the .1 ph I get from pulling the Vegas 110° weather lol.. my tank runs 80-83 because of that! It would be in the high 70’s if I pull the skimmer line back inside.

That’s an interesting data point. I live in a very mild climate and I don’t notice an impact on my tank temperature. I’ve lived in some very hot places, and I’ve often wondered if pumping outdoor air to my tank would have a big impact on the temperature.

 

[Miami Reef]

Congrats! I’ll be interested to see how higher nutrients do. :)

Thanks.

PO4 will be around 0.5 ppm this time around.

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae. We determi…

www.sciencedirect.com

I probably shouldn’t be spilling my methods, but it’s an experiment, so I don’t know how effective it’ll be lol.


I have too much fun with my tank lol

 

[Troylee]

Thanks.

PO4 will be around 0.5 ppm this time around.

Effects of phosphate on growth and skeletal density in the scleractinian coral Acropora muricata: A controlled experimental approach

Phosphate contamination can negatively affect corals, modifying growth rates, skeletal density, reproduction, mortality, and zooxanthellae. We determi…

www.sciencedirect.com

I probably shouldn’t be spilling my methods, but it’s an experiment, so I don’t know how effective it’ll be lol.

Don’t worry! I got a few things up my sleeve . J/k… I wished I would have paid more attention to the Efflo instead of taking it for granted it would just grow as it’s a easier coral lol.. that was the best grow out in that group I thought personally! I was more focused on the laser melon than anything and left the Efflo in a back corner of my tank the first 2 months instead of planting it!

 

[vandy]

I guess key takeaways that I’m going to try in case anybody stumbles across this thread:

*Increase alk from 7.5-8 to 9-10

*Aerate the water more

*Re-re calibrate your ph probes, and then get new ones if you still aren’t reading what you like

 

[Miami Reef]

I guess key takeaways that I’m going to try in case anybody stumbles across this thread:

*Increase alk from 7.5-8 to 9-10

*Aerate the water more

*Re-re calibrate your ph probes, and then get new ones if you still aren’t reading what you like

Aeration may or may not work, depending on the surrounding CO2 relative to the tank CO2.

The cup aeration test can determine that, but it looks like you’re on the right track.

 

[rishma]

^this! Good idea to do the test before doing anything with aeration in the tank.

 

[rishma]

*Re-re calibrate your ph probes, and then get new ones if you still aren’t reading what you like

I like this one. Re- calibrate if you don’t like the reading. If you still don’t like it, buy a new one

 

[Randy Holmes-Farley]

I guess key takeaways that I’m going to try in case anybody stumbles across this thread:

*Increase alk from 7.5-8 to 9-10

*Aerate the water more

*Re-re calibrate your ph probes, and then get new ones if you still aren’t reading what you like

Just an fyi, if you boost alk from 8 to 9 dKH, the expected pH difference is pretty small. About 0.05 pH units. :)

 

[Miami Reef]

Just an fyi, if you boost alk from 8 to 9 dKH, the expected pH difference is pretty small. About 0.05 pH units. :)

Is that solely from CO2 equilibrium? Environmental CO2 has an effect on that, right?

I’m curious how you calculated that. TIA

 

[Randy Holmes-Farley]

Is that solely from CO2 equilibrium? Environmental CO2 has an effect on that, right?

I’m curious how you calculated that. TIA

I show the details of how I did it here, but it’s not obvious how to do that easily. I did it using a spread sheet.

Chemistry And The Aquarium: The Relationship Between Alkalinity And pH

Randy answers many questions in this complex relationship.

reefs.com

And one can just sight along Figure 1 in that article.

But what I did here for a small change in alk is look at the change in the log of the pH. It’s a good approximation for a small alk change.

Log 9 - log 8 = 0.05 or a 0.05 change in pH

Looking at Figure 1 in the graph one can see it is roughly accurate even for a bigger change.

Log 3 - log2 =0.176

From Figure 1 we can see that corresponds to about

8.33 - 8.18 =0.15

So it’s close enough for this sort of purpose.