Whats going on with my alkalinity?

[discuspro]

Okay, I've been using Reef Crystals now for about two months solid and have been using 0 TDS RO-DI water to mix it to a S.G. of 1.026. I do not have a calcium reactor and I dose with Kalkwasser via drip. I do about a five gallon water change on my 50 gallon system about one a week.

It seems like my alkalinity is never high enough. On the seventh of this month I tested alk and I got a reading of 1.58meq/L :unsure . Then I added Kent Superbuffer-dKH until I got a reading of 3meq/L. Am I suppose to be supplementing alkalinity constantly? What am I doing wrong.

By the way my coral stock is pretty healthy with about 30 small colonies/frags. Calcium levels are usually around 340-380ppm by supplementing Kalkwasser. Do I need a calcium reactor? Anyone want to give one away, hehe :lol

[blueboy]

i am having issues with reefcrystals right now too(see my thread from last week). i have been going back and forth with them about it, or rather i keep calling , they don't return my call. i'm not real happy with them right now, i feel like this problem is not being taken seriously. i suggest you call them about it, their number is 1-800-322-1266. i heard from a little bird that we're not alone in this, yet when i called the guy implied that he didn't believe me. i even got new test kits to confirm. mix up a fresh batch, let it set for 24 hrs, then test the calcium, mine shows 100ppm! with an aquarium pharm. test kit, and doesn't register at all with a red sea kit. LMK, i'm very interested to find out.

[discuspro]

I'll mix up a batch and test it in the schools lab in a few days.

[NaCl_H2O]

IME a Kalk reactor and Ca reactor will dose Ca to maintain levels, but won't do much to increase levels. On the other hand, a Kalk reactor is a good device to maintain stable PH, and a Ca reactor does very good at maintaining stable dKH. Getting both runing correctly and stable is a fairly long process (for me anyway) of 2-3 months. Getting Ca where you want it, regardless of salt brand is easiest by using anhydrous calcium chloride (e.g. Kent Turbo Calcium) and then the Ca &/or Kalk reactor can maintain the level.

Also, 5g water changes for a 50g (10%) per week sounds light to me.

[discuspro]

I'm talking about alkalinity: mostly HCO3 (bicarbonate), which is used 2times more than calcium in calcification of coral. My calcium levels are fine I thought at 340-380ppm. It seems like my alkalinity continues to be reduced more than I've expected. Has someone else used Reefcrystals and not have a calcium reactor observe their alkalinity decreasing without supplementing buffer? I would have thought doing water changes would have kept alkalinity stable but what I've done has not and I've got to supplement by chemical addition, which I don't want to have to do forever.

[GaryP]

Remember that there are other other things that deplete alkalinity besides calcification. Primarily it is depleted by low molecular weight organic acids produced by a variety of things in the system.

I'm not sure where you are getting the 2:1 stoichiometric ratio for calcification. The last time I checked the chemical reaction for calcification is:

Ca + CO3 ----> CaCO3

Both calcium and carbonate are divalent, therefore the ratio should be 1:1.

[discuspro]

This deals with a fair bit of the mechanics of my research:

http://myweb.stedwards.edu/~dholden/copyrighted.jpg


I've made up some new Reef Crystals water and I'm going to let it stir for a solid day and them take samples in the lab. I figure my bicarbonate supply is being used up faster than it is replenished and I stupidly thought a salt mix would take care of it for me. I'm going to have to buckle down and get a calcium reactor or steal one from you guys, hehe :P

[Richard]

Often you will precipitate out some calcium and carbonates when you let the water sit a day or more.

I always mix the salt and use it within a few hours. Reef Crystals has always mixed up at around 3 meq/liter and Ca just under 400 for me.

[blueboy]

that's about were i thought it should be. i switched from IO to get the higher calcium.

[discuspro]

So blueboy, you haven't been using Reef Crystals?

[matt]

I think it's pretty common to need more carbonate supplementation if you're keeping stony corals and using KW drip as your only means of calcium/carbonate replenishment. Since your ph is probably nice and high from the KW, you'd probably be fine just using baking soda as a carbonate supplement.

[discuspro]

Just tested the freshly made, well-mixed for a day Reef Crystals and at a S.G. of 1.026 I read 400ppm of Calcium and 3.15meq/L alkalinity. Sounds good to me my coral must be eating up that carbonate very quickly then.

[Bug_Power]

I've got the other problem my Alk is WAy high....gunna have to get an RODI system to get the alk down. My well water has high amounts of Calcium already, and after adding in some kent salt I get a parcipitate on the sides of my container. I once left some mixed water for about 5 days and it was a paste on the walls of the container.

[discuspro]

What about phosphates and heavy metals? I would be scared to use anything other that RO-DI unless you know exactly what is in your water. Get that RO-DI system, actually what kind of tank do you have? I mean SPS, LPS fish-only, etc?

[blueboy]

yes, i have been using reef crystals, just switched from IO about 3 waterchanges ago.

[discuspro]

Have you knoticed problems using the Reef Crystals?

[GaryP]

This deals with a fair bit of the mechanics of my research:


What does photosynthesis have to do with calcification? Last time I checked corals hadn't been moved to the plant kingdom. :) What about respiration? Then you would be back to 1:1.

[fishypets]

I had the same problem using Red Sea. Switched to Tropic Marin Pro and all my problems went away.

[blueboy]

hey, i'd switch to any salt that would make all my problems go away! LOL

[discuspro]

GaryP, check this article out, this is where I got that info from:

McConnaughey, Ted A.; Adey, Walter H.; Small, Allegra M.; Community and Environmental Influences on Reef Coral Calcification. Limnology and Oceanography, Vol. 45, No.7 (Nov.,2000), 1667-1671.


This is how I believe it works: one bicarbonate supplies the eventual carbonate(CO3) that combines with the calcium. The second bicarbonate supplies the zooxanthellae (symbiotic dinoflagellates), which gives the photosynthesis part of the equation it's place, with carbon dioxide to produce carbohydrate (CH2O) and eventually ATP through photophosphorylation. The photosynthesis part with it's carbohydrate and ATP production is needed because it supplies the proton/calcium antiport with energy to move hydrogen across the CBE and eventually combine with bicarbonate to continue the cycle.

There is a 1:1 ratio for a carbonate and calcium ion to make calcium carbonate but the make the cycle work, during the day, an additional bicarbonate is needed to make the ATP to pump hydrogens out from between the CBE and skeleton, according to McConnaughey et al. It makes sense also because the coral would need to take hydrogens out of the space in order to precipitate calcium carbonate because if it wasn't the pH would continue to stay high enough to keep the calcium carbonate from continuing to precipitate.

Respiration does bring up a good point that the oxygen would be consumed as it was produced and thus return one of the carbon dioxides back to the equation. I believe this: during the dark cycle respiration occurs and photosynthesis cannot, then we would see what you are speaking of with the 1:1 ratio of bicarbonate used per calcium carbonate precipitated. Also, calcification would be slower at night because it is not assisted by photosynthesis. But, during the light cycle photosynthesis would be occurring making calcification faster and would need that extra carbon dioxide to supply the zooxanthellae. So, during the day 2 bicarbonates would be needed and at night 1 bicarbonate would be needed.

I’m just theorizing and I definitely don’t’ have it all figured out at all, just trying to think through it.

[Bug_Power]

What about phosphates and heavy metals? I would be scared to use anything other that RO-DI unless you know exactly what is in your water. Get that RO-DI system, actually what kind of tank do you have? I mean SPS, LPS fish-only, etc? Phospates = 0, Nitrates 0 We checked for metals and found none. I was really surprised. However my water comes from the ground water about 500 feet from the lake. I was concerned until we tested it and it came out ok. I'm going to go ahead and setup a RO-DI system at the other house.

BTW what's the difference between Ro and RO-DI. Is the deionization really that important?

[GaryP]

DI basically acts as a polisher to remove anything that sneaks through the RO membrane.

[GaryP]

OK Discuspro, not really to make your life difficult, but basically because I don't have anyone else around here to have this discussion with; how about non-photosynthetic corals, such as Dendronephthya or Nephthyigorgia? They still use calcification to build calcium carbonate spicules don't they? How does photosynthesis fit into your model in that case? I really didn't plan on turning this into a Master's oral defense, but that is the kind of questions you could expect.

In all honesty, and that was my original point, we are talking about two seperate but related mechanisms. You are looking at it from the standpoint of an overall net mass balance, and that is fine. My point was that calcification and photosynthesis are seperate biochemical mechanisms that a zoanthellae containing coral contains. The role of CO2 and/or carbonate are both important of course. Mostly it's just a matter of intellectual hair splitting. But I just love splitting hairs. :) I understand the biochemisty of sugar production and phosphorylation and all that. Just don't ask me to recite the Kreb's cycle from memory. I've slept several thousand times since the last time I looked at it. I used to do research on developing bio assays based on quantifying ATP with luciferase for industrial applications. I even wrote papers on it for a couple of journals that are so obscure that you would never find them in a million years.

You should see the glassy eyes in the room when I try to bring up stuff like this in a MAAST meeting talks. I usually stop as soon as I start to hear snoring. Maybe we can get bstreep to jump in here. He used to be a biochemist. Then we can have this thread all to ourselves, because everyone else will be asking themselves "what the heck are they talking about?" :)

[GaryP]

BTW, I checked at Barnes and Noble and they just ran out of the latest edition of Limnology and Oceanography. Darn my luck. :)

[discuspro]

That whole model is not my idea but McConnaughey's. I'm just trying to make sense of it, I've found what I believe are loop holes in it as well. McConnaughey was making that model only for photosynthesizing calcifyers and since that is the bulk of the stock in my tank that is why I've applied it to try and figure out why my alkalinity was dropping more that I was expecting.

Before I put words into McConnaughey's mouth I need to read this one again. I don't know if it'll be copyright infringement but I could email you a copy of that journal article. I get it through the account that St. Ed's U has.

Last night I was also thinking why would a second bicarbonate need to be broken down when the CO2 that would be needed could be supplied with the surrounding CO2 in the water? Maybe it would be more energetically stable for a bicarbonate to split into water and carbon dioxide? Like I said I need to read it again to get it fresh in my mind but I can't remember if McConnaughey et al. proved this by experiment or not.

[GaryP]

OK, think about this. Terrestial plants photosynthesize too, right? How much bicarbonate is present in the air? None? That doesn't mean that it may not be converted into bicarb in the plant tissues though, so you have me on that one. As a matter of fact it would just about have to be mostly converted to bicarb in the intercellular pH. Where is a botanist when we need one?

The thing is that CO2 is going to be fairly rare at the pHs we are talking about. You need to look at the pkH for CO2 and bicarb.