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#1
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High alk and low Ca ?!?!?
Randy,
I have one for you. Why is my alk raising over time and calcium failing? My alk is up to 13.1 dkH (4.69 meq/l) and finally was able to get my calcium from 320 to 400 by adding about 60 mg of CaCl. I do not add buffer. I thought Alk should be flat at about 8 dKh and that I should only have to adjust calcium every so often. What do you think is going on in the tank (or reactor)? Temp = 78 deg F pH = 8.2 to 8.3 SG = 1.025 Tank = 210G using RO/DI and only IO salt. Ca = 400 Alk = 13.1 dKh/4.69 meq/l Nitrate = 2.5 Magnesium = 1410 Strontium = 10 I am using a calcium reactor (Korallin 1502 and seconary reactor) and currently have it set for effluent rate of about 60 DPM and CO2 at 30 DPM (output effluent is about 6.6 pH) TIA Scott |
#2
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What kind of media is in the reactor? If there is dolomite that contains more magnesium than your corals are using, then alkalinity and magnesium will rise and calcium will fall over time.
What are you using for top off water? The RO/DI alone?
__________________
Randy Holmes-Farley |
#3
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Randy,
Using ARM for both the first and second calcium reactor chambers and use RO/DI alone for the top off (spectrapure top off kit). Interesting. I'm testing for Magnesium, but have not added any yet said is at 1410 ppm; so, do you think the ARM is dissolving lots of Magnesium? OK, looks like I should test two additional parts of my system: 1) test freshly mixed IO for Ca, Magnesium and Alk. 2) test effluent of calcium reactor for same. Will post results when I get them. Scott |
#4
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Another issue is that IO has fairly high alkalinity recently, but still lowish calcium (350 ppm Ca++/4 meq/L alk). So water changes with it will allow alkalinity to rise relative to calcium overtime.
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Randy Holmes-Farley |
#5
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Randy,
Here's my results and it looks like IO is the issue which brings up much larger issues 1) IO alk appears much higher than NSW 2) ARM alk is much higher then normal from Caclium reactor (but his is prolly influenced by IO level). 3) Need instructions from Habib on how to use Magnesium kit for measuing effluent of Reactor. Can you simple dilute with RO/DI or are there any special instructions. 4) How the heck am I going to control Alk if IO starts high and reactor is putting even more in. Can't back off effluent/CO2 since that will starve tank of Calcium. 5) IO calcium is low, reactor Ca appears low, so am I stuck feeding CaCl to tank to maintain? 6) Relationship between Alk/Magnesium and Ca. In my tank Alk and Magnesium are high, but Ca is low. So, how to fix? that I'll discuss with you after presenting the results below from water, to RO/DI to IO salt mix to tank then finally to calcium reactor: I) Source Water: First, conductivity/TDS measurements of water: Water after softner using Potassium Chloride = 1230 uS Water after RO = 086 uS Water after RO/DI = 025 uS Alk of RO/DI water turns orange after one tiny drop so basically below the detection limit of test kit (less than 0.3 dKh) Conclusion: RO/DI is fairly pure give it does not have much dissolved solids (salts) that conduct electricity at all and extremely low Alk. II) IO: Mixed 5 gallons of RO/DI water (above) with enough IO salt bring specific gravity to 1.025 measured with refractometer. Water was broght to 78 deg F just like tank water. Total mixing time was about 2 hours. Alk = 13.8 dKh/4.91 meq/l (checked twice) Ca = 360 ppm Magnesium = 1230ppm Conclusion: Ca/Magnesium a bit low but within NSW range. HOWEVER, Alk is off the charts at 13.8 dKh. III) Tank: 210G of IO mixed with RO/DI and maintained at 78 deg F with pH swing from 8.2 to 8.3 Alk = 13.1 Ca = 390 (been adding 1 teaspoon of CaCl/day for last week) Magnesium = 1410 IV) Calcium Reactor: Running Korallin 1502 with second reactor. All media is ARM. CURRENT effluent is 1 drip per seocnd with 1 bubble CO2 every 5 seconds. Effluent pH after 2nd reactor is pH=6.9. Alk = 56.2 dKH Ca = 740 ppm Magnesium = 1350 straight or 1620 if divide measurement by half. NOTE: Salifert warns that Ca/Alk will interfer with Magnesium results if outside 300 to 500ppm. My Ca above measured in a 740 so I divided sample by half and got the 1620ppm reading. [Ask Habib about how to use Magnesium test kit for measuring effluent of calcium reactor] Conclusion : ARM media is definitely dissolving but Alk appears much higher relative to Ca/Magnesium. [Randy - what's the ration of Ca to Alk again? 20ppm of Ca to how much Alk (dKh)? Scott |
#6
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Randy,
If Oceanic is low in Alk and high in Ca/Magnesium, then would this salt provide me a means of bringing my system back to equilibrium or at least closer to NSW? Looks like just turning the Calcium reactor down or off isn't going to do it if I stick with IO. Side note. I've been using IO for about 7 years now and do not ever remember having trouble with high Alk. This is very shocking to me and if there is an IO rep on this board I'd like to hear from him/her. PS I've lost one SPS colony out of 10 and most likely due to the extremely high Alk of IO. I see no other reasons to explain the sudden loss. I've read anecdotal reports of both high and low Alk (> 11 and < 6.5) resulting in RTN/CTN and I believe I have yet even more evidence to suggest you don't want your tank water much different than NSW. Scott |
#7
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More data points. Had a fellow reefer check my tank and IO water with his Alk test kits (we are all using Salifert in case I didn't mention earlier) and he got:
Tank = 12.5 dKh/4.46 meq/l IO (after 4 hours mixing at 78 deg F) = 9.3 dKh/3.31 meq/l I'll test my 5 gallon bucket of IO tomorrow afternoon to get an Alk reading after 24 hours of mixing. WRT my tank, I've dialed back my calcium reactor and will start very small partial water changes with Oceanic to see if I can get my Alk back to at least 10 dKh. PS Some have recommended adding a weak acidic like vinegar (acedic acid) but I think partial water changes with Oceanic might be a better way then adding acid unless I can get pure (reagent) grade acid. I feel funny adding kitchen grade acid to my tank. Randy - any thoughts on adding acid to a tank to get the buffer down? Scott |
#8
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IO alk appears much higher than NSW
Yes, nearly all salt mixes come out higher than NSW. Your early values seem unusually high for IO, and may be an off batch (or an off testing kit). The second set of values look fien to me (3-4 meq/L) If the IO is low, I'd boost the calcium in water change batches with calcium chloride to 450-460 ppm Ca++. That should solve all of the problems at once (if caused by the IO). You need not add it to the tank, un less the media has excess magnesium. Conclusion : ARM media is definitely dissolving but Alk appears much higher relative to Ca/Magnesium. [Randy - what's the ration of Ca to Alk again? 20ppm of Ca to how much Alk (dKh)? I wouldn't conclude that. There is too much testing uncertainty to make such a conclusion. FWIW, the rise in alkalinity in the reactor effluent is about what one expects in the effluent based on the calcium rise (the alkalinity is even a tad low, based on the calcium rise). I would not add acid. I'd back off a bit on the reactor,and add some calcium chloride if necessary, to boost calcium. The alkalinity will then decline. Vinegar does not lower alkalinity at all. A mineral acid (like HCl) will lower the alkalinity, but I don't recommend it. FWIW, I've not seen convincing evidence that 13 dKH is harmful. It may even be beneficial to calcifying corals.
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Randy Holmes-Farley |
#9
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Randy,
Will let system stablize over the next week with Calcium reactor dialed back then will prolly start adding CaCl and/or small partial water changes with Oceanic. Thanks. Scott |
#10
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That sounds reasonable.
Good luck!
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Randy Holmes-Farley |
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