Difficulty Raising Alkalnity

[demariners]

So, I was able to calculate my dosing to stabilize my Alkalinity and Calcium. My alkalinity is at 10.3 dKh and my Calcium is around 440. So based on the Red Sea reef foundation program they ask for me to try to get to 12.3 dkH and 465 Calcium. So I went ahead and dosed about 1dKh worth before my dosing schedule. I would assume at this point my Alkalinity would then raise by about 1 dKh when I test after the day at the same time I normally would. So I did a test and it is back at 10.3 and calcium dropped about 25 and it now at around 415 ppm. How is this possible? I want to add my Salinity is at 1.025 and Magnesium is about 1500 ppm. I do not want to add more buffer and try again as my calcium might drop again. Any ideas what is happening?

 

[atarjanyi]

You are at the point where adding either Ca or Alk will trigger abiotic precipitation. This means that by trying to get to the Red Sea numbers you will only deposit more CaCO3 in your impeller chambers and on your heaters. This is good for Red Sea supplement sales and bad for you in added maintenance and replacement of impellers. Corals will grow well with Ca in the low 400's and alkalinity in the 7-9 dKh range and you will see very little abiotic precipitation.

I used to chase these high numbers with a diy calcium reactor and tons of extra pump maintenance. Now I'm just using Kalk with a small amount of diy 2 part as needed. It's a lot less stressful just watching the tank than tearing apart pumps to clean out the impellers every few weeks. And trying to maintain numbers that just aren't going to happen.

Alex

 

[rt67ghy]

This link is very helpful:
http://www.advancedaquarist.com/2002/11/chemistry

 

[bertoni]

I suspect that you just need to add more supplement, but the dosing might be causing some abiotic precipitation. Is there any sign of tannish or white buildups on surfaces?

The higher pH of most supplements plus the higher alkalinity level can encourage extra growth, which could be part of the problem. I'd try dosing some more alkalinity, and then measuring the level about 10-15 minutes later, to see what's getting into the water column.

 

[demariners]

My pH is a little high around 8.35 most of the day and 8.28 is during he night. If I add more supplement it doesn't seem to do much. It appears that when I add some more supplant I get a higher pH and it still precipates out. I am thinking when doing so I should add calcium at the same time. I think that's the step I am missing. Usually my calcium is good but the alkalinity is lower then I am trying for. So I end up adding just ALK to supplement my dosing. I do not see any brown or white build up yet. When I add 1 DKH of supplement I test it is spot on and does not precipates out. Only after 24 hours does it shoot back to 10.5.

 

[bertoni]

If you think the high pH is causing precipitation, which makes sense, you could try dosing baking soda a few days. It doesn't raise the pH the way most supplements do. Adding calcium will encourage more precipitation, especially with the level fairly high already.

Since it's taking 24 hours for the alkalinity to drop, I'd guess that the issue is consumption, although there's some possibility that the precipitate is staying in the water column long enough to cause problems with the test. Alkalinity test kits work by titrating an acid, which will redissolve any precipitate in the water column, so I'd be very cautious at this point. Still, I suspect that the issue is not precipitation.

 

[demariners]

Well I typically use Sodium BiCarbonate to do my small adjustments which I think does not raise the pH at all.

So how could it be consumption if everyday I test at the same time for the last week and it is between 10.3-10.6 dkH every time and the Calcium is always between 440-445. When I add alkalinity and only alkalinity via Sodium BiCarbonate. I test for alkalinity after about 30 minutes and it does check out at 11.5 or so which is exactly what I dosed. Then after 24 hours it shoots back down to 10.5 however the calcium for some reason dips to 410-420 from where it was stable. Not sure if I should just leave everything alone and be happy where it stands. Again, i am only doing this because thats the directions Red Sea has explained for me to go to use their product and the salt I use (Pro Salt) has higher Alk, Ca, and Mg so i want it to balance out as well when i do a small to large water change.

 

[demariners]

Could my high magesium be the culprit? Around 1500 ppm right now. Seems to go up and never down.

 

[bertoni]

Magnesium generally helps prevent abiotic precipitation. 1500 ppm should be fine.

 

[demariners]

Hmmm.....that's odd. I do notice that sometimes it does not really go down and in fact rises. Very weird. I think I am going to add some calcium when I add alkalinity. That's the only thing I am not doing at this point.

 

[outssider]

1 dkh drop in a day is not much....I lot of tanks will consume way more on a daily basis (mine does). I think part of the problem is shooting for dkh of 12+. If you took a poll here on RC, i'll bet you would get an average dkh of 8.5.

 

[demariners]

My consumption is around 2.3. Not 1

 

[demariners]

Bump.

Still continue to have the issues I am having. I have waited a week and my Alkalnity is stable and so in the calcium. I went ahead and did a water change last weekend and noticed that my alkalinity remained stable at 10.03 and calcium at 430, mag is not more at 1450 since the water change. I went ahead and dosed a little more then the stablized amount and it will simple never rise. It stays at 9.9-10 daily at the same time each day and will not go up. if i dose lets say 1 dKh manually at the same time I test 15 minutes later and it is indeed 1 dKh higher. I test 24 hours later and it is back to being where it was and stable.