High Alkalinity and Calcium

[Chuck Spyropulos]

How high is too high? I finished reading some of Randy's articles and the only downside I could find regarding high alkalinity and calcium is:

1. higher chance of calcium precipitation
2. more calcium build-up on impellers, stirrers, etc

My calcium is around 500 ppm right now and my alkalinity is around 5.5 meq/l (15.4 dkH). I could easily reduce these by simply turning down the water flow and/or reducing the CO2 flow rate through my calcium reactor. But I am also running GFO which supresses alkalinity. Also, I have just recently begun running GFO and I may want to increase the amount of media in my fluidized bed reactor from 1 mg per gallon to 2 mg per gallon to help with the nuisance algae. Therefore I would rather leave the calcium reactor alone to account for any decrease in alkalinity that may occur as a result of increasing the amount of GFO. If there is no problem doing this then it would give me a good margin as far as alkalinity is concerned.

So far, everything in the tank is doing quite well at the current Ca and Alk numbers. Mg is around 1250 ppm and pH runs around 8.2.

In view of the above, are there any reasons (besides the 2 given above) to decrease the Ca and the Alk?

 

[MikeG]

My only reason is to allow room for error. If your calcium reactor fluctuates at all you are already pretty close to the upper limits of saturation. I tend to run much lower around 425-450ppm and 9-10dkh to allow for more of a cushion in case something were to go wrong. I also run very heavy on GFO at about 150g with about 200 gallons.

 

[Dave McReeferson]

That is some high ALK you've got there. What seems off to me is that you would run everything so high, yet run your Mag so low, is there any particular reason you do this?

Edit: To be more specific, it seems to me, if you choose to run your Ca and Kh at such highly elevated levels, it would be wise to also run elevated Mg levels to prevent excessive precipitation and provide a more "stable" or maintainable balance...

I am just curious if you had some reasoning behind your low Mg levels I had not considered...

 

[Chuck Spyropulos]

Mg

Mg is low not by choice and has been at this level since my tank was set up
(1250).

Randy suggests 1250 to 1300 so at least i fall in the recommended range, albeit on the low side. Also, it seems that Mg has always been at 1250 in my tank and tends to vary less with time in contrast to Ca and Alk levels in my tank. For that reason and the fact that Ca and Alk are already high enough, I don't see a reason to increase Mg. According to Randy's articles, as long as Ca and Alk are maintainable, Mg levels are ok.

That is some high ALK you've got there. What seems off to me is that you would run everything so high, yet run your Mag so low, is there any particular reason you do this?

Edit: To be more specific, it seems to me, if you choose to run your Ca and Kh at such highly elevated levels, it would be wise to also run elevated Mg levels to prevent excessive precipitation and provide a more "stable" or maintainable balance...

I am just curious if you had some reasoning behind your low Mg levels I had not considered...

 

[Chuck Spyropulos]

Post

I just read your EDIT... I was posting at the same time, sorry

I never had a problem with excessive calcium precipitation. Also, for some reason it seems that the acros in my tank always do better with higher than normal alkalinity. Anyone else have this experience?

I think that excessive precipitation would definitley be a risk if I dosed kalkwasser and my pH was around 8.4. But I stopped running kalk when I moved the sump to my fishroom.

That is some high ALK you've got there. What seems off to me is that you would run everything so high, yet run your Mag so low, is there any particular reason you do this?

Edit: To be more specific, it seems to me, if you choose to run your Ca and Kh at such highly elevated levels, it would be wise to also run elevated Mg levels to prevent excessive precipitation and provide a more "stable" or maintainable balance...

I am just curious if you had some reasoning behind your low Mg levels I had not considered...

 

[Greg Hiller]

>But I am also running GFO which supresses alkalinity.<

I've heard this before, but not really experienced it myself.

>1. higher chance of calcium precipitation
2. more calcium build-up on impellers, stirrers, etc<

Yup, that can be pretty annoying if you have pumps seize up on you. I had a Tunze powerhead seize up on me and it cost several hundred $ to replace.

Just be careful your pH never goes very high or the snow will begin to fall.

 

[ReeferMedic]

>But I am also running GFO which supresses alkalinity.<

I've heard this before, but not really experienced it myself.

Same here. I've heard it from a couple of members, but never had it happen in my system. I run enough for 900 gallons on a fairly heavy stocked 600 gallon system fwiw.

 

[smcnally]

Wow! 15.4 dKh seems awfully high. Mine got right around 15 dKh and I ended up suffering STN as a result. I would be very careful about keeping your Alk that high and if you lower it I would do so very slowly.

 

[maurod]

As far as the ratio of Mg to Ca, I thought a ratio of close to 3:1 was mentioned on Randy's site somewhere.

 

[Chuck Spyropulos]

Snow

Hi Greg. Yeah, one of his articles mentions that the "snow" is induced by high pH along with high Ca and Alk. Well I don't want to have a Tunze 6100 go bad....I think I'll try to slowly and carefully reduce the Ca and Alk....

>But I am also running GFO which supresses alkalinity.<

I've heard this before, but not really experienced it myself.

>1. higher chance of calcium precipitation
2. more calcium build-up on impellers, stirrers, etc<

Yup, that can be pretty annoying if you have pumps seize up on you. I had a Tunze powerhead seize up on me and it cost several hundred $ to replace.

Just be careful your pH never goes very high or the snow will begin to fall.

 

[Chuck Spyropulos]

Ca and Alk

Could it be that if a tank is running at nearly the bottom of the recommended ranges for Alk and Ca that GFO causes Alk to drop? I'm trying to avoid this because it happened to me in the past. The only difference now is that my Alk and Ca are way higher AND my pH runs lower (8.2 vs 8.4 previously when I ran a kalk reactor). Since I began running the GFO this time, I have not experienced any reduction in Ca or Alk. Can I make the conlcusion that the higher Ca an Alk is responsible for the GFO not having the same effects as it did before? If the answer is yes, then how far can I drop the Alk and Ca such that the GFO has a neglible effect on Alk?

Don, what levels do you maintain for Ca and Alk?...just curious to see if my theory is correct...

Same here. I've heard it from a couple of members, but never had it happen in my system. I run enough for 900 gallons on a fairly heavy stocked 600 gallon system fwiw.

 

[Chuck Spyropulos]

Ratio

I must have missed that in my readings but it sounds about right:

Assuming Ca is at 425, Mg should be at 1275.

As far as the ratio of Mg to Ca, I thought a ratio of close to 3:1 was mentioned on Randy's site somewhere.

 

[ReeferMedic]

Don, what levels do you maintain for Ca and Alk?...just curious to see if my theory is correct...

My calcium is usually arouind the 420 range and alk usually hovers around 9 or so. I try to keep my mg closer to 1500. It seems to have an effect on hair algae. All are tested with salifert test kits. This is with my reactor running at a slow stream. I'll bump the ca and alk up a bit every so often with two part, but it's probably not necessary. My ph runs about 8.2 or so with the lights on and drops slighty over night.

 

[buddie]

if you are keeping alk that high and take in frags from systems with much lower alk you will have more chance of rtn or'' alk burn'' if there is such a thing

 

[Chuck Spyropulos]

Tonight I turned down the C02 flow into my calcium reactor to slowly reduce the Ca and Alk. I'm going to aim for Ca = 475 ppm and Alk = 5 meq/l (dkH = 14) .

 

[Chuck Spyropulos]

After turning the C02 down by changing the effluent pH C0 2 valve controller to 7.0 from 6.8, the Ca decreased to 485 ppm and the Alk is at 5 meq/l (14 dkH). Another thing is that the pH is slightly higher at 8.26 vs 8.18 (a good thing!). I guess the excess C02 was also bringing down the pH. It could also account for, at least partially, my algae problem. For now, I think I'll leave things alone and see how it goes.

 

[Liam]

What is the purpose that folks run their alk so high,NSW is around 7 dkh.

 

[smcnally]

What is the purpose that folks run their alk so high,NSW is around 7 dkh.

A lot of people don't keep their alk nearly as high as Chuck is. I'm curious as well though about why he's keeping it so high. The "recommended" Alkalinity level of a reef tank is 9-11 dKh.

 

[Chuck Spyropulos]

Alk

Yes my alk was a little high. However, the recommended range that I have read is between 3 and 5 meq/liter or 8.4 to 14 dkH. In general the recommended alk for reef tanks (according to many books: Tullock, Fenner, Delbeek and Sprung) is higher than natural sea water. I have also read that when not running kalkwasser, that it is better to run elevated alk to keep the pH stable at a reasonable level (not sure where I read this but I think it was one of Randy's articles).

For me alk levels of around 11 to 13 have worked really well over the last 7 years. pH remains solid at 8.2 and the corals "looked happier" better polyp extension, better growth rates and less algae problems (except recently). At the lower levels (8 to 10) the pH, at least in my tank, seemed to vary way too much (around 8.1 to 8.4).

Right now the Alk is around 13 since I reduced the C02 flow out into the Calcium Reactor. Calcium is running around 475 now.

What is the purpose that folks run their alk so high,NSW is around 7 dkh.

 

[Greg Hiller]

>What is the purpose that folks run their alk so high,NSW is around 7 dkh.<

Of course the ideal calcium, alk, and pH parameters are those of the ocean. However, some of us run calcium reactors which sometimes suppress the pH a bit. To compensate for this and make it a bit easier for corals to put down skeleton, some of us (myself included) tend to run alk a bit high (usually 2.7-4 meq/l) and calcium >450 ppm.