Alk bouncing all over

[slojmn]

I have been struggling to maintain an alk between 6.5-7.0. I just bounce all over the place. Here are my alk/calcium readings over the past few months.
11/14 8.0/465
11/25 7.7/455
12/2 7.0/440
12/20 6.0/480
12/21 6.7/490 (added baking soda to bring alk more in line with ca.)
12/28 7.0/480
1/7 7.7/475
1/14 7.0/455
1/19 5.8/420

I hate chasing numbers but everything I read about zeo says keep alk at NSW levels and I feel like my alk is low and ca is always high in relation. So any suggestions to get this more stable? Bob assures me that some issues with my sps corals is probably related to alk levels. I run a calcium reactor with a ph probe and solenoid. I slowed down the drip down slightly when I recieved a new drip adjuster a couple weeks ago. As the alk drops so does the calcium. I would like to get alk up and keep calcium where it is. I am slowly adding 1 tsp of baking soda over today and this evening. Would it be prudent to add 1 tsp of baking soda every 5-7 days and monitor params? Is this to much/to often? I tested my make up water, I use Kent and alk is definately low, 4.5. I am planning on mixing the Kent with IO 1/3-2/3 proportion to see if the alk will come up somewhat with water changes over the next few weeks. My hope is to get stable alk/ca and keep the two more in line...6.5-7.0/430-450. Any suggestions or advice welcome.

[gqjeff]

Alicia, Ca will fall into the proper proportion with Alk between 6-8.. DO not try to adj your Alk to your Ca... Also is it alk at 4.5 or dKH? If dKH you are actually running very high Alk.. With 7 Alk you should be roughly 410 CA and thats about ave for NSW... Also with looking at what you are wanting its not possible if they are in proper propportions.. 6.5-7 alk will not yield 430-450 Ca and there is not reason for CA that high... Also whats are your Mg #'s? I have found that really helps with keeping Alk stable if Mg is at NSW levels.. shoot for 1250-1300 MG... I would prob try speeding your bubble count or slowing your drip to raise the alk since its that low.. This artical may help you also.. I just browsed through it and it talks about the old days of 8-12 Alk but still I think it might give you some useful info...

http://www.wetwebmedia.com/calcalkmar.htm

Jeff

[Pikeman]

Alicia, FWIW, I never mess with my drip rate. I usually try to keep it relatively steady by just "eyeballing" it day to day. What I do watch closely is the bubble rate. I've found that if I keep close tabs on the bubble rate the alkalinity will remain pretty steady. My rational for this is that once the CO2 gets the pH down in the reactor, the only thing that matter is how much more CO2 your putting in to dissolve the media. More CO2 ---> more alkalinity. Less CO2 ---> less alkalinity. My last two cent is to not think of your calcium reactor as a calcium reactor (its misnamed), its really an alkalinity reactor that just happens to give you properly proportioned calcium to boot.

Good luck,
Jeff

[gqjeff]

Alicia, here is also a very good article for you and will help shed lite on the subject.
http://www.advancedaquarist.com/issues/nov2002/chem.htm

Things like this can be frustrating but you will overcome it if you do some reading..

Jeff

[slojmn]

Jeff,
alk readings are really the dKH readings from my Salifert test kit. The 4.5 dKH was my make up water. According to the test kit table the higher the dKh the higher the alk in meq/L...so 4.5 dKH(make up water) is 1.60 meq/L and the 5.8 dKH(tank water) is 2.06 meq/L. Bob has suggested I stay between 6.5-8 dKH.

Also is it alk at 4.5 or dKH? If dKH you are actually running very high Alk.. With 7 Alk you should be roughly 410 CA and thats about ave for NSW...

7 alk is not even on the Salifert table...16 dKH (KH value)=5.71 meq/L (alkalinity value). I am confused by your quote above. The article you linked me to is a good one. I get the relationship and know that I need to bring my alk more in line with Calcium. The calcium is quite a bit higher in relationship to the dKH readings. They are out of whack. This is one of the scenarios in that article. The suggestion is to bring alk up slowly without messing with calcium numbers. Baking soda seems to be the way to do this but to keep it stable maybe the salt change and tweaking my reactor is part of the answer.

Pikeman, I have my calcium reactor set with a ph probe and controller, it is only releasing CO2 into the reactor when the Ph in the reactor reaches 6.5. Should I lower this or increase it?? If I increase it then more CO2 will be bubbling into the reactor. Does this increase the dKH or decrease it?

[Pikeman]

Alicia, as I control my Ca Rx manually, I am probably not in the best position to help you. (While I like advanced instrumentation, I follow the belief that simpler is usually better). My, perhaps simplistic, response is that you are likely controlling the wrong variable, Ca Rx pH, instead of your tank alkalinity. As such, your controller is adjusting the CO2 input independent of your tanks need. Unless, of course your controller has the ability to regulate the CO2 input based on pH AND the continuous monitoring of your tanks alkalinity level. (But I doubt it)

In answer to your question, when your Ca Rx controller calls for more CO2, you will get a resultant increase in your alkalinity production.

To remedy this, I would try to manually control the CO2 bubble rate for a while, erring on the low (less bubble) side until I could determine my tanks alkalinity demand and then very slowly increase the bubble rate accordingly to meet the steady state demand. Also, since you've purchased a drip controller for the Ca Rx output, it sounds as if you have good control on the residence time in the reactor and the pH should take care of itself.

[gqjeff]

Jeff,
alk readings are really the dKH readings from my Salifert test kit. The 4.5 dKH was my make up water. According to the test kit table the higher the dKh the higher the alk in meq/L...so 4.5 dKH(make up water) is 1.60 meq/L and the 5.8 dKH(tank water) is 2.06 meq/L. Bob has suggested I stay between 6.5-8 dKH.



7 alk is not even on the Salifert table...16 dKH (KH value)=5.71 meq/L (alkalinity value). I am confused by your quote above. The article you linked me to is a good one. I get the relationship and know that I need to bring my alk more in line with Calcium. The calcium is quite a bit higher in relationship to the dKH readings. They are out of whack. This is one of the scenarios in that article. The suggestion is to bring alk up slowly without messing with calcium numbers. Baking soda seems to be the way to do this but to keep it stable maybe the salt change and tweaking my reactor is part of the answer.

Pikeman, I have my calcium reactor set with a ph probe and controller, it is only releasing CO2 into the reactor when the Ph in the reactor reaches 6.5. Should I lower this or increase it?? If I increase it then more CO2 will be bubbling into the reactor. Does this increase the dKH or decrease it?

Alicia, sorry I screwed up and put Alk instead of dKH, Alk will be around 2.5 meg... Yes I think that artical will help you get things in order.

Jeff