Ideal Alkalinity for SPS growth?

14 foot reef · Jul 7, 2020

My LFS runs at 12 DKH been in business for 35 years and has been a guest speaker at Macna a few times. I'm running my Alk at 10+ now as his corals are the best in the state and my acclimation is easier if I but coral from him.
Mentioned above, is a statement of "skeletal growth is faster than tissure in a high alk and low nutrient system."
I'm not arguing the point, I'm just wondering if there is scientific proof of this theory, or is it just speculation.
Like a broken record, stable seems to be the key, not the actual number.

blasterman · Jul 7, 2020

14 foot reef said:
Mentioned above, is a statement of "skeletal growth is faster than tissure in a high alk and low nutrient system."

I think it's hooey myself

I've seen tip burn many, many times and induced it many, many times. Tip burn looks nothing like skeletal growth.

I've had mostly better growth with higher dKH, but mostly in smaller tanks. I've seen the best growth in reactor driven tanks and those typically run dKH on the lower side unless it's augmented.

Hard corals adapt to pH / carbonate ratios via producing more calcite in their skeletons which is denser and slower growing than typical calcium carbonate based skeletons. So, I think the real questions is; if alk is kept stable, which we all agree is the real key, does it matter? IMO, that should be the discussion.

BRS did a test recently where they measured SPS weight growth in higher alk/calcium systems and they did find the higher levels produced better growth. My biggest caveat with this test is I think the test duration needed to be longer.

wphan · Jul 7, 2020

I keep mine between 7-8 dKh. As always just keep it constant.

SamMule · Jul 7, 2020

blasterman said:
I think it's hooey myself I've seen tip burn many, many times and induced it many, many times. Tip burn looks nothing like skeletal growth.

How can you tell them apart?

This is all very interesting information. I agree, I would like to see a longer test from brstv on this subject.

Cory · Jul 7, 2020

Low nutrients keep alk at 7dkh. High nutrients keep alk 11-12dkh offsets high no3.

pdxmonkeyboy · Jul 8, 2020

^ this. Plus having phos readings within the margin of error foe the test kit. Kind of scary. I mean people do it, i did it for a long time but found much happier tank around .1.

Ike · Jul 8, 2020

robdareefer said:
The higher the ALK the faster the skeleton growth, if the the other perimeters that contribute to the flesh growth are low such as po4 and no3 then the flesh can't keep up with the skeleton then the tips get burnt because the flesh is to thin on tips.

Last I saw there's not much scientific evidence to support it, though I've seen some people and companies claim it. A lot of claims were based on one very limited study of skeletal growth in popcilipora that a lot of people jumped to false conclusions about.

"burnt tips" seems to be more of a nutrient related issue than it is an alkalinity issue. Us long time hobbyistsn used to maintain 12-15 dKH with much issue, then 10 was the norm. Now, I'm happy anywhere between 6-8.

Ashish Patel · Jul 8, 2020

I ran mine for years around 8.5-9.5. However, overtime I realized in my tank SPS tend to do better with overall health when around 7.5 (No less than 7 and no higher than 8). Can't comment about the growth but honestly I think ppl don't keep it low since there is less room for error but if you keep it that low to begin with it you still have your tanks range. I experienced simliar thing with temperature, My tank does fine at 73-75degrees.

Alk on natural coral reefs is around 6.5DKH. Acros grow like weeds, take them same acros and put them in an aquarium in high Alk is a reason why 99% of wild acros never make it past 1 month.

Recreating ocean parameters has always been a win win IME. Follow that is only strategy I will need.

Reeferjones · Jul 9, 2020

I was always told pick a number between 8 and 9 and keep it that number forever
and everything will be happy. for me this is what works.

vetteguy53081 · Jul 9, 2020

Everyone has a Magic number
Mine is 9

Djsreef · Jul 9, 2020

Par definitely plays into alk and nutrients, Also flow as Well. I think color may be affected by alk and nutrients too.

ISFNick · Jul 9, 2020

Keep it around what your salt mix alkalinity is. If it’s 7, keep your alk at 7 (tropic Marin pro reef).

if it’s 9 DkH, keep it at 9 (HW Reefer)

stability is the key. Keep in mind that coral vendors keep their alk around 7-9. They know best. Above all though, keep your alk STABLE.

alexiowa · Jul 9, 2020

Mine is at 10 and doing well for quite a while. It’s high but not a crazy number. Just monitor everything like you’re supposed to and don’t let nutrients get too low or too high. Done

Streetcred · Jul 9, 2020

Time marches on but everything else stays the same ... "Reef Aquarium Water Parameters", Randy Holmes-Farley.

Mr. Azwell · Jul 9, 2020

Jfarooqpak said:
So you have no tip burn AND your corals are happy? What is the question again? Sorry i dont get it

He's both making a statement and asking a question at the same time: I've seen contradicting information out on the web about alkalinity for safe SPS growth. He is saying, "I keep mine at 9.5 and there is no tip burn". Other say to shoot for 10. Still others say sub 9. What gives?

I agree with you SamMule, there does seem to be a lot of conflicting data out there about alkalinity. It is also the most difficult parameter to understand and control as well. You have problems if it is too high or too low and the N/P ratio does seem to be something that is part of the coral health as well. I wonder what Randy Holmes says about it....

Mr. Azwell · Jul 9, 2020

Streetcred said:
Time marches on but everything else stays the same ... "Reef Aquarium Water Parameters", Randy Holmes-Farley.

Streetcred, you beat me to it!

Mrtakeoff53 · Jul 9, 2020

I tried running my Alk at 9-9.5 but the tank really just didn’t like being there. Corals didn’t seem happy and would never stabilize there. I let it slowly (talking MONTHS here) slide to between 7.8-8.3. Trying to nail a certain number is too difficult so I give myself a range to keep it in. My corals grow like crazy. I run a higher nutrient system too. NO3 at around 5-10 and PO4 at .08-.10. I have some algae but have amazing colors. Some might say my PO4 is way too high but it’s what my system likes, so I leave it. CUC and tang take care of the algae but my rocks are almost 100% covered in coralline algae so that helps beat back anything too ugly. But the key, like most have said, is STABILITY.

Mr. Azwell · Jul 9, 2020

Mrtakeoff53 said:
I tried running my Alk at 9-9.5 but the tank really just didn’t like being there. Corals didn’t seem happy and would never stabilize there. I let it slowly (talking MONTHS here) slide to between 7.8-8.3. Trying to nail a certain number is too difficult so I give myself a range to keep it in. My corals grow like crazy. I run a higher nutrient system too. NO3 at around 5-10 and PO4 at .08-.10. I have some algae but have amazing colors. Some might say my PO4 is way too high but it’s what my system likes, so I leave it. CUC and tang take care of the algae but my rocks are almost 100% covered in coralline algae so that helps beat back anything too ugly. But the key, like most have said, is STABILITY.

How do you adjust your pH?

Shawn_epicurious · Jul 9, 2020

As I have recently learned, there is a lot of bad data out there on alkalinity. Or at least... data most of the reefers I’ve talked to here would absolutely disagree with. Have a look at the suggested SPS water parameters on the lonk below. If you google SPS Water parameters” this is always the 1st site that pops up...

SPS Reef: (Ideal Tank Parameters, Lighting Requirements, Flow)

A full SPS Reef can be a mesmerizing thing of beauty that many hobbyists thrive for. Hobbyists from around the world challenge their reefkeeping abilities

www.spsreef.com

and then... look at the pic below for the salt I use. It suggests an Alk of 12 *dKH. I keep mine around 8.07

Mrtakeoff53 · Jul 9, 2020

Mr. Azwell said:
How do you adjust your pH?

I don’t. I have 5 kids and my wife in the house all day and the pH stays pretty low. Usually 7.6-7.9 in the summer and 7.9-8.1 in the winter (I live in FL and shut everything in the summer). I know that if my Alk is lower than about 7.5, my pH will drop below 7.65 If pH higher than 8 in the summer and 8.2 in the winter, alk is above 9. I never chase pH. The main factors in controlling pH are alk level and dissolved CO2. I can’t control CO2 well in a house full of people so I accept lower pH and keep alk STABLE. My corals don’t mind. SPS take a few weeks/months to get happy in my tank and then grow like weeds. You just have to observe your tank, watch for patterns and see how it reacts to your inputs. I have an APEX so that helps me watch the pH which helps me determine Alk level. I run kalk in my ATO water. That’s all the dosing I do.