My tank is almost two years old now and I've never had great luck getting coraline algae or zoanthids to grow. My coraline grows in little spots on the rocks and occationally on the glass, but generally covers high calcium areas like snail shells. My zoas tend to grow well when put into the tank but after a month or so stop completely (probably due to a lack of coraline to grow on?).

I'm using Seachem Reef salt, here are my recent readings before and after a water change:
Calcium - 440ppm before, 440ppm after, api test
KH - 8dkh before, 10dkh after, api test
PH - 8 before, 7.8 after (measured mid lights on cycle), hagen test
MG - 1200ppm before, 1215ppm after, salifert test
SG - 1.024 before, 1.025 after
Temp - 78 - 82 degrees

Everything looks good to me except the MG is clearly low and the PH seems low for a mid-day reading, it probably drops down to 7.6 or lower at night though I haven't measured it. I am currently not dosing anything and do 20% water changes weekly. I'm taking some water into my LFS this weekend for a phosphate test but I just changed out my chemipure elite which had just expired.

Should I dose MG and if I do will it increase my CA readings?

My KH is 10 but seachem is notorious for high borate, does this reading still seem acceptable?

Any other suggestions for increased coraline and zoa growth?

What are your nitrates?



Zoanthids don't need to grow on coralline.

I'm not sure the hagen test is an accurate brand. In any case, alkalinity is more important than pH, and your alkalinity and calcium levels are in the normal ranges. Magnesium is only slightly low, but not that bad.

Here's some info on a salifert boron test kit:
http://www.advancedaquarist.com/issues/sept2003/chem.htm

Nitrates, Nitrites and Ammonia are all below detectable levels. Thanks for the link, any other suggestions on what I might be missing?

0 nitrates could be an indication that your tank is too "clean" for zoanthids and some other soft corals to grow well. However, coralline algae should be growing. You could try to do some heavier feeding.

Low Mg can affect Zoa growth.
Some Zoas don't do well at all in low Mg levels.
If you have a tank that is otherwise balanced and healthy but Zoas just don't do well in your system, check to see if your Mg is low.

Haha, really? I know my post was a little long but come on

I forgive you, do you think 1200 falls into that category?

yes 1200 is way low add some epsom salt to your next WC. Lighting has a lot to do with coraline as well as zoas. Low magnesium with the levels of calc and alk you said you had is almost unbelievable, not to call you out. Really I would try adding magnesium and probably some iodide. You didn't mention lighting but I'm guessing you don't have enough actinic as well. If your KH is 10 your Ph should be stable! I would go so far as to suggest an abundance of TDS. If you want to fix the problem I would sugges several large WC and probably an upgrade in lighting. LOL. If you've ever been diving the ocean really doesn't have that much coraline.

+1

And, laks, thanks for that advice. I added the Alk to my top-off and I'm slowly raising the dkh in my tank to a stable 9. Ph still swings a little but is expected and not stressed.

I've got 150W MH, 14000K bulb + PC actinic suplemental lights on my tank, I've read some coraline prefer lower light levels so perhaps I just need to introduce more coraline species that like bright light. I agree that the MG is kind of unbelievable given the CA and KH levels I have, but I trust the API and Salifert tests and I've tested several times with same results. Possibly TDS, I am using RO for water changes and distilled for top-off so not likely, I also only feed 3 times a week.

I don't have a skimmer or fuge so I kind of doubt that my water is too clean but sure that's a possibility.

My plan of attack now is this...
1) Dose MG to get it above 1300.
2) Introduce more coraline with something like garf grunge.
3) Do more ph testing

Thanks everyone for the input

LOL coraline grow right up under my 400w 20k without a problem. Clean water is preferable, IMO garf grunge is kinda like mark weiss products, just make you mad you were dupped. Get the Mg up and runs some carbon til you get a skimmer.

I'm already running chemipure elite, picking up some more purigen this weekend.

I actually have a skimmer but don't use it, wasn't really planning on it since I do weekly WC and don't have a lot of sps.

Haven't read much about garf yet, but they do advertise having a lot of coralline varieties in their grunge, would you suggest any other products to introduce coralline or do I have to buy some rocks and start scrubbing?



Sorry that was confusing. I do have both a skimmer and a fuge, but I do not use them any longer. I have so many wires and hoses going in and out of my tank already that I have been trying to simplify it a bit and these didn't seem to benefit the system enough to justify the complexity for me.

Just wanted to follow up. I replaced the chemipure elite last weekend and tonight I gotta say my zoas are certainly looking much better. The ones that were almost gone are extending and noticably larger. I even see some new babies. So it was probably my phosphates.

Now to get that coraline growing...