Ideal Alkalinity for SPS growth?

[SMB]

My RS salt alk is 11. I keep the tank at 10.5 and it has been that for 18 months. If I go lower my pH drops to 7.8/7.9. With the alk at 10.5 the pH is 8.0/8.1. With a pH prob I know what the alk is because the correlation is spot on when I test alk. Pretty easy way to monitor what's happening. I don't have tremendous growth rate but the corals look great.

 

[Floppyfish]

Just saw this in my email. Didn’t read all 3 pages to catch up completely. I manage 3 reef tanks for a museum. The largest being 2500 gallons. My goal is to keep the Kh above 8 and Ca above 400. Never allow the pH below 8 and we keep our temp at 74. We gave exception growth of Acropora cerviconis. Dont have any of the other more exotic color morphs so I can’t say much about them.

 

[Mr. Azwell]

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.

I've used sodium carbonate which keeps the alk higher and raises the pH when needed. Sodium hydroxide is too corrosive to tubing and is a bit more dangerous to mix than Na2CO3. I use my APEX to monitor the pH and keep it at 8.2. Alk is usually 9 to 9.5. My coral seems "happy" but I do have a bit more problems with acros than I would like. I might try easing the pH setpoint down gradually over the next few months and see if that helps.

Thanks for the info.

 

[mdromaine55]

I seem to find a lot of contradicting information.
Some say high, like 10dkh (red sea)
Others say low, like 7.5

I'm keeping mine at 9.5 right now. My SPS all seems happy. I see a lot of people talking about tip burn with high alk. My nutrients are pretty low and consistent. .03 phosphate and 2 ppm nitrate.
According to some of the stuff ive read, my acro tips should be burning.
What am I missing?

 

[@phokusonmi]

If there is one thing I've learned over the past 6 years, it's that there is no ideal. Every tank is different, even separate tanks in the same room are different.

Mine is good high alk and high phos

 

[thermoJoe]

One advantage of running higher Alk is somewhat more stable pH. Alkalinity is simply a measure of buffer capacity of the water (i.e., how much the pH changes as you add a given amount of protons). I use to keep my Alk around 7 using a Ca reactor, but I always worked at keeping the pH from dropping below 7.7 at night. Consequently, I also used a kalkwasser reactor on the ATO and set the ATO to only come on after the lights went out. That worked fine for many years. Then I got a trident and found there were rather large swings in Alk occuring over the day (~ 1 dKH) due to Ca(OH) added at night from the ATO. These large swings cause the trident to often double sample. The double-tap sampling took a while to figure out over conversations with Neptune Systems (turns out the Trident tries to predict what the sample value will be and if the measured value is too far from its prediction, it resamples). So, I started running Alk around 9 dKH and just let the ATO add as needed.

 

[EJReef]

I seem to find a lot of contradicting information.
Some say high, like 10dkh (red sea)
Others say low, like 7.5

I'm keeping mine at 9.5 right now. My SPS all seems happy. I see a lot of people talking about tip burn with high alk. My nutrients are pretty low and consistent. .03 phosphate and 2 ppm nitrate.
According to some of the stuff ive read, my acro tips should be burning.
What am I missing?

0

 

[Rex]

Thanks for posing the question, I'm still working to balance tank 5 months in and learning from following discussions like this!

 

[KTTX]

This has worked great for me.

 

[SamMule]

This has worked great for me.

What is that? Can you explain?
According to that I should be running like 380 calc instead of 440-460.

 

[jeffww]

I try to run at least 8.5 (ranges from 8.5 up to 10) and Ca I do not measure anymore and maintain purely through 2 part dosing. Last I checked Ca was around 460.

 

[hotdrop]

Initially i found that high alk had more precipitation so I dropped down to 8 and things have worked fine. I think there is a difference between fine and optimum but im not a commercial operation and 8-8.5 is easier to maintain

 

[KTTX]

What is that? Can you explain?
According to that I should be running like 380 calc instead of 440-460.

Calcium in relation to Alkalinity.
I run 420 to 7.8-8. I use to run 440 to 10 but it was burning my SPS. Since I changed to this, that issue has gone away

 

[Ashish Patel]

There is actually alot of sound advice on this thread. I think I will target 8DKH in my new setup. Since I prefer lower ALK anyways and I know as things grow it will naturally deplete so I would be fine to let it drop to 7.5DKH before increasing 2 part. If it goes above 8DKH then I know I have an issue that needs to be solved. In the past this was a good indicator of if increasing light works based on 2 part consumption, If it didnt go up then its too much light. Had the opposite happen when I didnt test CA for 6 months and 2 part consumption dropped considerably since CA went to 250.

 

[Kjeldh]

Switched salts to TM which measures 7.8 - 8.1 dkh with the Hanna Alk checker. With this as a stable base, my alk dosing is easier to maintain in the 8 ish range

 

[Reefcowboy]

Most successful sps tanks I've seen run between 8 and 9.
I notice at that range my corals look the best

 

[BAUCE]

Calcium in relation to Alkalinity.
I run 420 to 7.8-8. I use to run 440 to 10 but it was burning my SPS. Since I changed to this, that issue has gone away

What are your phosphates and nitrates? If higher could that be why they were burning?

 

[Charlie’s Frags]

What are your phosphates and nitrates? If higher could that be why they were burning?

I was thinking they were being burned because of lower n/p with high (10) alk.
The burning stopped bc alk is now 7.8-8. I don’t think it had anything to do with calcium to alk ration

 

[BAUCE]

I was thinking they were being burned because of lower n/p with high (10) alk.
The burning stopped bc alk is now 7.8-8. I don’t think it had anything to do with calcium to alk ration

thats what I was trying to get at but its been a long day and I mixed it up somehow. I should have said lower there. Thanks for the catch.

 

[Charlie’s Frags]

thats what I was trying to get at but its been a long day and I mixed it up somehow. I should have said lower there. Thanks for the catch.

I know the felling