DkH

[fencer]

What is the best DkH to have optimal growth for SPS. Assuming all other parameters are adjusted or okay. Please choose one and round up or down to the nearest whole number

[mark]

not sure but might do a survey of TOTM write-ups.

[marie]

I don't know that there is a "best" DKH, anything within the parameters you set for the poll is fine and the dkh in my tank bounces around all those numbers :lol:

[globaldesigns]

Mine is at 7, but that is because I run Zeovit, otherwise IMO 9-11 is good

[fishytime]

Dont take my TOTM writeup as something to go by....my dkh is low and Ive been struggling to get it up.....wait a second....that didnt sound good:redface:

[whatcaneyedo]

For me I have to keep my alkalinity up around 11-12 dkh in order to keep my pH up in the 8.0- 8.2 range. There is so much carbon dioxide in my house (especially in the winter) that if I let my alkalinity fall down to 7-8 my pH will also drop to 7.6-7.8

I do everything from drawing my skimmers air from outside to dosing kalkwasser in conjunction with my Calcium reactor to growing macro algae and leaving the top of my system open for better gas exchange. But still I fight with low pH.

[RuGlu6]

There is NO best dkh, per say.
it will depend on your calcium
higher calcium requires higher alkalinity and visa versa.

[fencer]

I assuming a Ca of 450 ppm/ Mg 1400 ppm is good for SPS. My DkH hovers around 8( a bit lower) which is required for Ultralith program. I run a Calcium reactor and have a lot of rock in the tank. I am always interested in how a person who gets a tiny frag can grow into a monster within a year. "Marie's" tank comes to mind. I do realize some corals grow faster than others. I was thinking high DkH and Ca may aid in Ca uptake by Acros. What are they doing riight that I am not. I guess I really need to see someones tank (locally) who has been raising(growing) SPS successfully.

[sphelps]

8 to 9 I think on average is best. If you start going over 10 you'll get alk burns on some of the sps corals. I have read however that some salts have higher levels of metals such as boron which actually gives a false Alk reading on test kits and if you're using such salt you need to maintain higher Alk levels around 11-12 to achieve actual alk levels of 8-9. Not sure on all salts but I know Ocean Pure is one of them. I believe the "best" alk level will depend on the salt you use and the types of equipment you employ, a little experimenting is necessary to determine what is best for your system.

I also seem to recall that natural seawater usually doesn't exceed 8 dkh.

[Snappy]

sphelps8 to 9 I think on average is best. If you start going over 10 you'll get alk burns on some of the sps corals. I have read however that some salts have higher levels of metals such as boron which actually gives a false Alk reading on test kits and if you're using such salt you need to maintain higher Alk levels around 11-12 to achieve actual alk levels of 8-9. Not sure on all salts but I know Ocean Pure is one of them. I believe the "best" alk level will depend on the salt you use and the types of equipment you employ, a little experimenting is necessary to determine what is best for your system.

I also seem to recall that natural seawater usually doesn't exceed 8 dkh.

I agree unless you run a ULNS like zeovit for example, then it is recommended your DKH is a bit lower. My experience with Ocean Pure salt wasn't great so I don't recommend it for an SPS tank.

[whatcaneyedo]

I didnt experiance an alkalinity burn on an acropora until my alkalinity shot up to +20dkh due to having too much flow through a calcium reactor. The flesh just pealed off the acro almost instantly. I havent lost anything like that while keeping my alkalinity in the 11dkh range.

[sphelps]

I didnt experiance an alkalinity burn on an acropora until my alkalinity shot up to +20dkh due to having too much flow through a calcium reactor. The flesh just pealed off the acro almost instantly. I havent lost anything like that while keeping my alkalinity in the 11dkh range.
Every tank is different, but have you tried a lower dkh? I rarely hear of anyone having good results at that level. What kind of salt do you use?

[fencer]

Hmm..comments are interesting. The DkH of sea water is 7.5. Because I run Ultralith I have to keep it around that mark. I have tried raisng my DkH even 1 point I found I was tossing in a lot of Carbonate. I find it hard to even consider a Dkh of 9 as trying to raise it that high would probably throw my other prams out of wack. For those who have consistently high DkH I wonder if it isn't the salt that is doing it or not using RO/Dionized water for make up.

[marie]

I like to run with a DKH of 9 just because I don't test very often and when my corals (and coralline algae) go through a growth spurt, alk and cal levels drop fast.
At 9 DKH I have a little bit of leeway before it drops disastrously low :redface:

[fencer]

Hi Marie
What do you think is causing this rapid growth in your tanks? That only thing that I can figure out that would drop your carbonate level that fast is clams.

[marie]

Hi Marie
What do you think is causing this rapid growth in your tanks? That only thing that I can figure out that would drop your carbonate level that fast is clams.

Thanks to my regal angel I have no clams in this tank...coralline algae and corals are the only calcium suckers that I know about in there

[Aquattro]

With my 150, my SPS grew so fast that I couldn't give away frags. My Ca was about 400ppm, and alk was anywhere from 8 to 11. Mg never got tested.
I used a large Ca reactor, which I suspect helped a lot, and 2x400w Radiums.
In my current tank, values are mostly the same, although I fight with my reactor (hence, and with alk) and Mg is ~1400ppm. It's been running almost a year and I have hardly any growth.
I doubt I've had enough growth in this year to match what I used to get in a month. So personally, no idea what makes them grow like weeds.

I do have colors like I never had before, so it's a decent trade off.

[StirCrazy]

fwiw, it takes a lot higher than 13Dkh to burn corals, I maintained my alk at 13.2 for about 2 years. I found colors were more vibrant and growth was accelerated. if the alk fell below 11, I would know from the look of the digitata as its color would dull a little.

now it is good to see people trying to quote NSW alk levels but realy who cares :mrgreen:, what good is quoting NSW levels if you don't follow them all. a Ca level of 450 is definatly not a NSW level, Mg of 1400 is close but a little high for the average, but hey, I like a elavated Mg also.

my best growth and color was at 82 degrees, 380-400 Ca, 13.2 DKH Alk, 1350 Mg, 7.9 Ph, zero nitrate/nitrite/amon/phosphate and any others I can't think of right now. I used AB10K 250watt SE bulbs run by M80 ballasts, on home made reflectors.


Steve

[whatcaneyedo]

Every tank is different, but have you tried a lower dkh? I rarely hear of anyone having good results at that level. What kind of salt do you use?

I have a problem with low pH. If I let my alkalinity fall to ~8dkh my pH falls to around 7.6 at which point my controller shuts off my calcium reactor and sounds an alarm. So I have to keep my alkalinity in the high acceptable range for the sake of my pH.

However, if it wasnt for my pH problem I would aim to keep my alkalinity in the ~8dkh range as it seems to be more natural based on what I've read.

I use both Seachem Reef Salt and Instant Ocean. 50/50

I agree with you, every tank is different. Thats sort of why I posted in this thread in the first place. The question of 'which DKH is best for growth' seems kind of silly to me because everyone will have their own reasons and experiences that make their preference different. But rather than flat out saying that I thought I'd just state my side and let the questioner figure it out on their own. Obviously a dkh of 8 for me wouldnt be very good if it meant my pH would be 7.6

[Aquattro]

I think it's safe to say that as long as you're in a range, you're fine. Same as Ca. Anywhere between 360 and 450 will be fine.
Alk between 7 and 11 is where I aim, and as long as you don't fall too low, you should get good results in coral growth.

[untamed]

For me I have to keep my alkalinity up around 11-12 dkh in order to keep my pH up in the 8.0- 8.2 range. There is so much carbon dioxide in my house (especially in the winter) that if I let my alkalinity fall down to 7-8 my pH will also drop to 7.6-7.8

I do everything from drawing my skimmers air from outside to dosing kalkwasser in conjunction with my Calcium reactor to growing macro algae and leaving the top of my system open for better gas exchange. But still I fight with low pH.


Man...I could have written the exact same thing...word for word. My alk is higher than I would like (10) for exactly this reason. I've learned some very interesting stuff about my Kalk reactor as I've tried to use it to prevent overnight pH lows. (when you are hitting nightly lows of pH 7.6...you just can't ignore pH at that point)

[sphelps]

The way I see it is if you're pH is low at a natural alk level you've got other problems to address that aren't really solved by simply adding more carbonate to increase alkalinity. More than likely the amount of CO2 in the water is too high and instead of covering this issue with something else you should be looking at the source of the problem. 99% of the time it comes down to the calcium reactor for obvious reason, it runs on CO2. The problem is very few understand the science behind these reactors and simply set an internal or effluent pH and figure that's good. However there is much more to consider including media type, reactor design, effluent flow rate, circulation flow rate, and CO2 flow rate.

For example, you find your tank pH is lower than normal say 7.8. First off you know that tanks using a Ca reactor will usually have a little lower pH than tanks using other methods, but I don't think lower than 8.0 mid-day is normal. So what's the problem? Too much CO2? Most likely but what's the solution? Most would simply bump the alkalinity up by increasing the output of the reactor by increasing the CO2 input which will actually add even more CO2 to the tank. What you should do is adjust your reactor, you've obviously got too much dissolved CO2 coming out of the reactor, meaning either too much CO2 is being added, flow rates are too high or a combination of both. The reactor may also be too small for the demand of the system or be of poor quality and design.

Another alternative to adding more CO2 would be to add kalkwasser instead which actually reacts with the CO2 in the tank promoting a higher and stable pH.

I don't think anything over 10 dkh is good for SPS, mainly because I've never seen a successful SPS tank with an alkalinity that high. Even if you go through RC TOTM I don't think you'll see anything with much higher than 9 dkh.

[untamed]

Once you have concluded that your low pH is caused by too much CO2...solving that is difficult. My tank is just too sealed up and doesn't breathe well. The herbie overflows eliminate a lot of natural aeration that would normally help. It is a brand new house that is tight and even in the summer the air conditioning keeps the house cool and closed up. I need to feed my skimmer outdoor air somehow.

In my case, the Ca reactor has been shut off for quite a while and Kalk alone has driven up my Alk..thereby solving my low pH problem for the time being.

A number of my coral lay down more tissue at peak pH above 8.2 than they did when I couldn't get the pH above 8. I don't think there is much doubt that higher pH is better than lower (to a point of course).

I would be happier at an Alk around 8-9...but I'll push that higher in order to keep the pH above 8.

[whatcaneyedo]

I'm actually fine right now, my pH is in the 8.0-8.2 range. Two days ago I measured my alkalinity (Elos test kit) and I was sitting at 10dkh. Like I was saying, in the winter my house is too closed up and I have a lot of CO2 build up which drives down my tanks pH. In the summer I open up the downstairs windows and everything is fine. I dont think many of those guys on the Reef Central TOTM live up in the frozen north like I do. Many of their tanks are running chillers while my heater is still kicking on each day.

I run an old down flow PM 622 Calcium Reactor with course ARM media and a DIY 6" diameter 1' tall effluent chamber with fine ARM media. pH in the reactor is between 6.5-6.6 and controlled by an AquaController. There is enough flow through to maintain my tanks calcium and alkalinity at constant rates of ~420ppm and 11dkh respectively. I also run all of my top off (about 2 gal a day) through a knock off of a PM Kalk Reactor.

Do you see anything that I could do differently with regards to my reactor?