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What is considered stable for parameters?

So I'd like to know what your idea of stable parameters are.

Do you allow a fluctuation of 0.5ppm? Or is there a different range for different parameter?

Mainly interested in Alk / Ca / Mg numbers.

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I allow fluctuations in Alk & Ca as long as they are in the allowed range. I rarely measure Mg, although I expect it to have a good amount of fluctuation considering that I dose Mg supplement about once a month only.

Beside fluctuation ranges, I am curious what folks think of fluctuation & correction speed. I had very bed results when I attempted to immediately fix an off-parameter. I had much better results when I corrected the parameter value very slow.

My most extreme accident was when the RK didn't correctly turn off the pump for my ATO and flooded my 30G quarantine full of Zoas and some SPS+chalice with over 3G of kalk water. I noticed it after more than 5h after it happened because I was out at work. Everything was off, the salinity dropped under 1.020, the pH was high, and so on. I did repeated 10% water changes every 4h, making sure to pour the new WC (at ideal parameters) slowly into the QT. A few SPS & some Zoas that were closest to the ATO intake didn't survive - in fact the SPS bleached out by the time I noticed the problem. But the rest of them recovered fine, just very slow, some Zoas took over 1 week to reopen.

Another case for me was during the hyposalinity treatment I did for ich. The hyposalinity makes the pH very unstable, specially at the beginning of the treatment. I never attempted to fix it fast, I used baking soda dosing through ATO. And all the fish survived the treatment despite the huge pH fluctuations.

In other cases when I reacted fast to similar accidents or bad test results, the fast correction of parameters made me loose corals :(.
 
But what are your allowed ranges? Everyone's 'correct' range is different. Alk could vary from 7.6-11 depending on who you ask.


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But what are your allowed ranges? Everyone's 'correct' range is different. Alk could vary from 7.6-11 depending on who you ask.

Typically, my Alk is between 7 & 8 dKh, my Ca is between 400-500 ppm and my Mg is around 1300 ppm.

I am not taking special action as long as the ranges are:
Alk: 7-11 dKh
Ca: 350-500 ppm
Mg: 1200+

IMO this article is really useful to explain Alk, Ca, Mg and other params: http://reefkeeping.com/issues/2004-05/rhf/

From what I know, the normal Alk could be from 7 dKh to as high as 11-12 dKh. The "ideal" value depends on the amount of borate alkalinity in the tank. And some folks keep it higher intentionally considering that it helps corals growth, although a higher Alk level usually leads to more precipitation, so more maintenance/cleanup of equipment.

Most tests measure the total Alk, and most reef tanks have a somehow elevated borate Alk as compared with natural seawater, therefore the carbotane Alk which is the difference between total Alk and borate Alk could be low if the total Alk is only around 7-8 dKh. The corals need the carbonate Alk, the borate is usually present in artificial salt mixes in higher amounts that natural seawater in order to stabilize Ca & pH. IMO, it is important to know the borate Alk in your tank in order to determine the ideal total Alk value. I usually measure borate Alk twice a year, I have a Seachem test kit that can measure borate Alk beside total Alk.

Some folks try to keep the Ca higher than natural sea water, again considering that it helps increase the coral growth. The article I pointed to above, says that it doesn't and recommends a range close to the natural seawater.

As for Mg, there are opinions that it helps control algae blooms if its levels are higher. I do not know if it's true or not and what levels it needs to be to work against algae. My goal is not to have it lower than 1200 ppm because it is needed to prevent the Ca from precipitating, aka to keep a good level of Ca in the water.

Hope this helps.
 
It really depends on the parameter and who you ask. Imo a swing of 5 on cal isn't a big deal but a swing of .5 on alk would be. Everyone has their range that they like and what works for one may not work for others. Hell my first year and a half in the hobby I kept my alk at 12.2 dkh or as close to that as I could as that was what my salt was at and it seemed to work good for me. I would prolly still be keeping it there if it weren't for $$ and my nerve disorder getting worse. As I had a harder and harder keeping up I did notice a few things.

First took a while but finally was able to draw the conclusion when my alk was at 12.2 it always wanted to drop pretty fast at one point I was dosing 30ml of alk a day and that was barley keeping up. As I brought my target lower I noticed that the drop in alk became much slower I now shoot for 10 in my bedroom and well anything above 7 in the frag system as it is the one that gets neglected when I'm not doing well. Since I lowered my target in my room tank the amount of alk it needed decreased more than I thought it would. Now I can go a week without dosing anything and it will drop from 10 to around 9.2-4 where as before if I missed one dose I would drop a whole point in alk in a day.


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I am also curious about how much Mg, alk and Ca can fluctuate over a day, a week... and still keep acropora happy. I see the most coral reaction to alk change - how about you all? I would bet there is some wisdom in additive MFR directions for the max Ca, alk, Mg change per day.

SeaChem says
Ca: < 25mg/L per day

But per week? I would say <50mg/L of drift range per week to keep corals from crashing - less change is better.


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It gets interesting and challenging when doing numbers but every tank is different, I can't recall my parameters but took me a while to say I was ready for sps. I would test every week to check on the numbers to know the Cal Mag Alk/DKH and the depletion rate plus every month on nutrients Nitrates, Nitrites, Phosphates
All the fancy equipment I had to test were a Hanna colorimeter for the phos and the Reefkeeper for pH, everything else was done with two different test kits, kind of a PITA then came the Hanna Chekers, make things easier.
Red Sea, API and later Salifert were my choices for test kits, Elos was just a bit pricier for me since I was not willing to pay for the fancy Italian? endorsement...
The first thing I did in order for a stable system, was tackled the nutrients; battled for a while with Nitrates, tried one thing then another until a DIY sulfur based passive reactor did the job for me; still have it, full of new media and waiting patiently. Getting Cal, Mag and Alk to be at good levels I achieved it by dosing two part plus Mag following Randy Holmes? recipe I believe and also used Kalk at some point.
 
I work pretty hard fine-tuning my SPS frag tank to keep Alk between 7.5 and 8. I'm not as worried on Calc and I'm not sure why except experience hasn't shown me that a calc swing effects things as much -- so 375-450 seems to be ok. Magnesium doesn't drift much so as long as it's 1300+ I kind of ignore it.
 
I work pretty hard fine-tuning my SPS frag tank to keep Alk between 7.5 and 8. I'm not as worried on Calc and I'm not sure why except experience hasn't shown me that a calc swing effects things as much -- so 375-450 seems to be ok. Magnesium doesn't drift much so as long as it's 1300+ I kind of ignore it.

I always had amazing results at 7.5 - 8 Alk, however they were generally followed by tragedy. If the Alk drops to 7 overnight.......sometimes you can lose entire colonies. Or start to see RTN. I started aiming for 9-10 Alk with the same amazing results, and much less tragedy, because if the ALk drops to 8.5, or 8......you are still good. It tends to help catch the Alk when it starts to dip. I agree it's important to have all three in the correct range, however the Alk is the one that will sting. Once the tank hit the 2 year mark......I think it was......I noticed less of this overnight drop. However I believe it was from starting kalkwasser. I am back to using it now, and it is truly amazing. It can trend you Alk up though..........so it is not uncommon to see it in the 10-11 range. Over 12 and I have had "snow" in the tank. Too much calcium and a high alk will cause precip, right in the tank. Kind of neat to see............kind of. :(

Obviously if you are having success at 7.5 - 8, you are doing things right. Just thought I would note some of the problems I have found over the years. SPS is ADDICTING!!! Ha!!


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Never seen any negative affects to Alk up to 12.


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The question about health of SPS at higher or lower alk levels seems to tie into whether you run a nutrient poor or nutrient rich tank. High alk with a nutrient poor tank seems to lead to more STN and RTN. More importantly for me I have noticed a clear difference in color and less browning at low Alk levels. The coral and fluorescence at low Alk was readily apparent when I slowly switched.
 
I work pretty hard fine-tuning my SPS frag tank to keep Alk between 7.5 and 8.
Why are you trying for a lower alk range? I personally aim for 9-9.5 because alk seems more stable for my system in that range, and it's not too high or low...

I have a low nutrient system (low Nitrate/phosphate and few fish/no coral feeding) and also observed corals happier at a lower alk between 8-9.
 
I was getting a browning and brown tips at a higher alkalinity. Also less polyp extension. I moved it lower after doing some research and talking to a few folks with old, established SPS tanks and got much brighter colors. Also the frags that had browned out began coloring up again very quickly. I had gone high at first to try to stimulate growth, but I never noticed it was effective at that. I do notice a huge difference at low Alk though.
 
My 40b likes alk up in the high 9s but my 190 likes it mid 8s. Go figure! That's been slowing my transfer as I try to adjust the tanks to meet up closer. Now both are stable at high 8s so once I'm sure, I'll start moving coral.


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I target Alk 9-11. Seems that < 8 starts causing issues.
And I usually notice <9 because my PH drops.
Calcium and Magnesium I almost never measure.
 
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