Nutrients and colours confusing me!

[Wesps]

Hello all,

I've had a big break from feeding and never had any success with sps but I love them over anything else in the aquarium.
Finally bought an established aquarium that wasn't being looked after but had most of the equipment I'd need to get a good start.
Seems once it was moved with a massive water change I was had some high posphate but nitrates tested almost zero. Wasn't until I got some hanna checkers I'd been way out phosphate .8 and nitrate 12ppm.
It seems I was getting some leach from the live rock and at this stage I'm down to .2 and 10ppm.
Of course I already bought a few sps and I'm confused why with these readings I'm getting great colour and visible growth??

Aquarium 500l plus sump
2 Radion XR30 pro running ab+ 60% intensity
Mp60/MP40 reef crest and nutrient export
Vectra L1 return
GFO reactor
Carbon reactor
Small amount of bioballs in a reactor
Dosing nopox 8ml a day with dosing pump
Dosing 2 part
Ph 8.2
Dk 8
Calcium 500ppm
Salinity .025
Temp 25c

 

[ClownNut]

if the acro you got is green slimer, you are not even close to great color and the stylophora can be a lot more purple/pink
nutrient dont mean no grow, slower grow if you have higher po4.

 

[acro-ed]

There is a lot of misconception about zero readings being best for SPS.

IMO, the "right" amount of nitrate is not a set number, but rather a number that relates to all of the other variables of your system, including where you should keep your Alk at (Ca should always be in ratio to the Alk; ex. 8 dkh = 418 Ca).

Here are a few examples:


Right now I have a 150g (570L) with a rockstar skimmer (iTech 400) and a fair amount of PAR (2x radion pro, 4x T5, 1 UV/blue LED bar). It is mostly barebottom and has a ton of flow (L1, mp40qd, mp60). The tank is very low nutrient in its ability to "maintain" nutrient levels, but I feed at least 3x a day. The Nitrates stay around 20ppm even though the water is very "clean"; this is from waste being generated and breaking down due to the constant feeding. I would still say the tank is "low nutrient" even though I keep the nitrates up. The corals have been growing great at 8.1dkh Alk. Too much higher and I lost color, and too much lower and the growth wasn't as good. The color is quite good though across a broad range of SPS (at least 50 different acros in there). The Alk is not that stable though, and if I turn off the doser I lose about 0.5dkh per day (at least).

So clean water with deliberate ~20ppm nitrate, tons of flow, medium-high light, and mid-range alk = great all around color, average growth, and nearly all acros seem to love it.


Compare this to my former system: about 400g between 3 tanks that were plumbed together. They had sand, and were old and there was tons of detritus. The Nitrate and Phosphate were both high and the water was so filthy it had a yellow tinge to it when I did water changes. I had screaming high PAR (multiple 400w halides over everything, and LED and VHO supplements depending on tank) and I kept the alk at 9.6dkh. I had some acros that loved it (I had an Efflo the size of a dinner plate and others that grew huge); I had dark/brown zoox on the body of the SPS corals but also had seriously vibrant rim/tip colors.

So filthy water, screaming PAR, and high Alk = excellent growth, but colors too dark. Not every coral liked this setup.


A third example is a small 37g tank I had. It had a deep sand bed, a weak skimmer, high flow from an mp40 that was turned down, and a single Gen1 Radion mounted high (so lower end of PAR for SPS). This tank was neglected but did very well. It was set up for simplicity. I didn't run any dosers and just added a little 2 part whenever I would remember, which wasn't often enough. The average Alk was probably somewhere in the 6.4dkh range. The Nitrates would always test out between 0-1. Despite all of this, I grew a Miami Orchid acro and a wild Aussie Austera from single sticks to the size of open hands. The colors were reasonably good, but not amazing. The growth was slow to average, but not terrible.

So, low nutrient, low Alk, lower light, with high flow = extremely easy care, fair color, average growth, but nothing extremely vibrant or amazing.


I know this was long and drawn out, but sometimes examples help.

I can tell you right off the bat that your Alk and Ca are not in ratio. Pull a chart and try to balance them. Are you running a skimmer? Do you need the GFO? If the corals are doing good but you think the color could be better then you need to make SMALL changes over the course of several weeks to see if you are going in the right direction.

Hope this helps!
-Ed

 

[ca1ore]

I remain unconvinced that the conventional wisdom of vanishingly low nutrient levels contributes materially to success (or non success) with SPS; to the point that I don't even test for phosphate or nitrate anymore. I can tell from the appearance of my corals if something is amiss. I do test obsessively for Alk though.

 

[GSMclowns]

So what is the ratio between Cal and Alk?

 

[acro-ed]

Here is a partial chart:

Dkh meq/L Ca-ppm

6.50 2.32 407
6.75 2.41 409
7.00 2.50 411
7.25 2.59 413
7.50 2.68 414
8.00 2.86 418
8.25 2.95 420
8.50 3.04 422
8.75 3.13 423
9.00 3.21 425
9.25 3.30 427
9.50 3.39 429


It's not that you need to nail them together exactly, but the further they get out of balance the less stable they are... you could end up having a precipitation event, or precipitation issues when you add more chems. I can't say that having them "out of balance" directly relates to growth, but I can say that my corals seem to look better when these numbers are held relatively in balance.

IMO, the most important chemistry component is keeping the Alk stable.

Keep in mind that calcified coral is "calcium carbonate" and the calcification process depletes both Ca and Alk at a predictable rate (but slightly varying rate, depending on the coral). It's generally about 20ppm Calcium consumed for every 2.8dkh of Alk consumed. This is variable also due to Magnesium, and it is incorporated into the skeleton at varying rates as well. Mag in solution in your tank is/should be generally 3x the Ca. Other trace elements may also be incorporated (ever cut into an acro skeleton from a high phosphate tank? The skeleton is tinted green).

I'm by no means a chemist, but I hope this helps.

-Ed

 

[jda]

Best color and growth for me is always near zero, but not at zero.

.005 to .01 P
.05 to .1 N

FWIW - I found that color got better when I melted dead coral skeletons and added more to my tank than calcium and alk.

 

[cobra2326]

, slower grow if you have higher po4.

We do not know this at all. There are studies that show quite the opposite:
http://scholar.google.com/scholar_u...7ktM6gNMR9m4oPpGN14KMrFFw&nossl=1&oi=scholarr

 

[jda]

Nobody needed this study to see that a stag can grow OK with some elevated P... but .5 is not as bad as most people see... and stags are not all that hard to grow.

You should go with "slower if the higher PO4." There are more than enough folks that report the same thing across the board - I am one of them.

Heck, coral skeletons outgrow the pace of the tissue of PO4 gets low enough.

There are dozens of other studies that show that calcification occurs at a much higher rate with low PO4. Coralline, SPS, LPS, clam shells... anything.

 

[cobra2326]

Nobody needed this study to see that a stag can grow OK with some elevated P... but .5 is not as bad as most people see... and stags are not all that hard to grow.

So stags growth accelerates as PO4 increases, but others do not? You're downplaying the results. There are many factors at play. Perhaps it's high DOC, or when combined with high nitrate, or...

 

[ClownNut]

We do not know this at all. There are studies that show quite the opposite:
http://scholar.google.com/scholar_u...7ktM6gNMR9m4oPpGN14KMrFFw&nossl=1&oi=scholarr

interesting. basicly you reduce the density to increase growth.
it's like build a brick wall but leave some gap between all the bricks. I would like to see how will that affect the coral as the coral getting bigger.will it collapse on its only weight in long term? and how will they handle storms (i dont mean in aquarium.)
http://reefkeeping.com/issues/2006-09/rhf/

 

[ClownNut]

So stags growth accelerates as PO4 increases, but others do not? You're downplaying the results. There are many factors at play. Perhaps it's high DOC, or when combined with high nitrate, or...

also, what's the point to have fast growing corals when they are all brown?
:lolspin::lolspin::lolspin:

 

[jda]

If you want to believe the study, then believe it. There is too much evidence from good sources that say otherwise for me to give it much weight. There is also a study out there that says that using Granular Activated Carbon will cause your fish to get HLLE. Again, too much evidence that shows that this study is not likely on the mark either.

I have a professor in college tell us that he could commission a study to prove that your mom was really your dad, and your dad was your mom. He also said that some people would believe it.

 

[acro-ed]

I think it's fair to say that "some" detectable phosphate can stimulate growth. Zooxanthellae are algae-like dinoflagellates and P is a macro-nutrient.

I don't believe that a P reading of 0.5ppm will yield increased growth universally in all Acropora.

I do believe that it is possible, in the instance of the study with A. muricata, that this level did demonstrate an objective increase in growth. I just don't believe that the results are indicative of a similar level being beneficial for all and/or other acros.

I stand by my experience that some N and P, if properly controlled relative to the Alk/Ca/Mag and lighting, DOES give increased growth (and color). My Acro tank right now is doing very well in the range of ~20ppm nitrate and ~0.01-0.02ppm phosphate. I have found that when you zero out the N03 and P the acros get very pale (like a zeo tank, which I do not care for). I have also seen ultra low nutrient/zeo-type tanks have excellent growth, which just shows that there are varying conditions that can stimulate growth. I take "health" to be a combination of tissue density/color and growth, which is why I want to find a balance that keeps a fair amount of zoox density without getting too dark/brown. The denser zoox, IMO, is a defense against instability in the tank. Super pale acros crash hard when something goes wrong.

Just some thoughts....

-Ed