Crazy low Alk, but my Corals look better than ever

seth&angelle

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Im having a real hard time wrapping my mind around this. I have a well established 60 gallon SPS dominate tank that I run a small schuran jet stream calcium reactor on. My alk typically runs 6.7dkh to max 7.4dkh. 6.7dkh was more the norm as of late. Last month I was having issues with the circulation pump on the CalRx, so I did a total cleaning of the reactor, and I changed the pump. Since the overhaul, my alk has fallen to 4.8dkh to 5.1dkh. I’m trying not to freak out, and I don’t want to make any drastic changes. I’m slowly changing effluent rates, and I just lowered my ph ranges that control PH. I was closely monitoring my dkh after the overhaul, but I couldn’t stop it from falling with CalRx adjustments alone.

So now that you have that back story, to my amazement I do not see anything negative with the health of my corals with this incredibly low alk. My corals are growing and my colors on the sticks are actually improving.

All you stick experts who understand the science much better than I do, can you make sense of this? It is my intention to raise my alk back up to 7dkh in time. I would consider my tank to be ultra low nutrient system. If you guys need any other info on the system, let me know.
 

Sidius

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Just curious but what are you using to test the alk and is there a chance it's expired? I've seen first hand that my acro's started losing tissue at 5.9-6.0 dkh when I wasn't watching things closely.

If you're sure it's not the test kit then perhaps your corals have acclimated to the lower dkh?

I will add that I'm not an SPS expert, by any means.
 

Turbonut

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Im having a real hard time wrapping my mind around this. I have a well established 60 gallon SPS dominate tank that I run a small schuran jet stream calcium reactor on. My alk typically runs 6.7dkh to max 7.4dkh. 6.7dkh was more the norm as of late. Last month I was having issues with the circulation pump on the CalRx, so I did a total cleaning of the reactor, and I changed the pump. Since the overhaul, my alk has fallen to 4.8dkh to 5.1dkh. I’m trying not to freak out, and I don’t want to make any drastic changes. I’m slowly changing effluent rates, and I just lowered my ph ranges that control PH. I was closely monitoring my dkh after the overhaul, but I couldn’t stop it from falling with CalRx adjustments alone.

So now that you have that back story, to my amazement I do not see anything negative with the health of my corals with this incredibly low alk. My corals are growing and my colors on the sticks are actually improving.

All you stick experts who understand the science much better than I do, can you make sense of this? It is my intention to raise my alk back up to 7dkh in time. I would consider my tank to be ultra low nutrient system. If you guys need any other info on the system, let me know.
Lower nutrients= lower alk
 

29bonsaireef

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+1, If you run ULNS you can get away with low alk levels. In nature, on a coral reef, alk levels are pretty dang low compared to what most keep theirs at. The water is also very clean out there far from landmasses.
 

EmdeReef

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Low alk is usually not an issue other than slowing down the rate of photosynthesis and calcification. As long as kept stable it likely won’t cause major issues and if ph doesn’t drop too low which could cause stress and other issues. I’m not sure if anyone studied long term effects of low alk...

Edit: I would also make sure your test kits are accurate.
 
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seth&angelle

seth&angelle

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It’s a brand new salifert. I’ve tested all my other tanks with same kit and the alk readings are within the norm for those tanks.
 

phixman

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I too experienced this a while ago, I was running 4.8 and the coloration and growth exploded, I rose the number to 7.3 to lower the risk in case my doser malfunctions.
 
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phixman

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But there is very little info about this low kh.

Is just for fright or there is evidence that is not good in long term?.


What about kh levels in nsw?
I ran my system with 4.8 for 3 months
 

phixman

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And???

Did you have any problems?

How much coral did you stock!?

Guess the load of coral is important in this question.
Improved coloration, no issues , I was also feeding a bunch. I had mostly sps, euphyllias and some acans. No problems that I could tell
 
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CyberGuy

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I have the same low alk as you. I was freaking out when I used my Hanna Alk checker and it was 4.7. However, sps and lps in my 20 gallon was doing great with great coloration. I also have high nurtients and my phos was at 1.7. So I put in Rowasphos and do water changes and dose part 2 (alk) of 123+ Aquaforest and also dose Tropic Marine All-for-reef and have brought my Alk slowly over 2 weeks to 6.7 and phos down to 1.0. However my sps and lps are doing worse with better parameters. My hanna test kits and solutions are new.
I do not know if I should go back to having my alk at 4.7 and higher phos.

So strange. My small 20 gallon has no skimmer and no mechanical filtration. I only have a H.O.B refugium.
I did not not do any doising until I saw my alk of being 4.7.
 

melanotaenia

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I have the same low alk as you. I was freaking out when I used my Hanna Alk checker and it was 4.7. However, sps and lps in my 20 gallon was doing great with great coloration. I also have high nurtients and my phos was at 1.7. So I put in Rowasphos and do water changes and dose part 2 (alk) of 123+ Aquaforest and also dose Tropic Marine All-for-reef and have brought my Alk slowly over 2 weeks to 6.7 and phos down to 1.0. However my sps and lps are doing worse with better parameters. My hanna test kits and solutions are new.
I do not know if I should go back to having my alk at 4.7 and higher phos.

So strange. My small 20 gallon has no skimmer and no mechanical filtration. I only have a H.O.B refugium.
I did not not do any doising until I saw my alk of being 4.7.
Depending on how long your Alk was at that level the reason your corals are responding poorly is most likely a result of them getting used to the lower Alk and then now having it two points higher. For SPS in particular it is not as much about the DKH level as it is the consistency of the level you choose to keep (within reason, of course)
 
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