Ca, Mg, pH, Alkalinity & your Zoas

capture · 06/30/2008, 08:50 AM

Although our favorite corals don't require Ca & Mg to grow skeletons like SPS and LPS do, these parameters are integral in maintaining a healthy, thriving reef. Not to mention their balance and affect on pH and Alkalinity as well.

How do you go about keeping this important chemical balance in your tank? How large is your tank, what's in it?

Where do you tend to keep these levels (high, low, right on)?

Have any of these levels had a big effect on your zoanthids in particular? By keeping these levels where they should be, did your zoas/palys show better results? Worse? Did you make tweaks to keep your zoas happy?

With the increased numbers of reefers entering the hobby at the nano level, how could you help these nano reefers keep these levels inline with where they should be? These small tanks are much less stable than large tanks, that's why I ask.

Feel free to contribute as you see fit.

flyyyguy · 06/30/2008, 01:07 PM

I will just add that low alk can be a huge culprit in allowing polyps to do the "meltdowns" we all know and love. Like capture said, while polyps may not need maintained levels of alk, calcium and mag to build skeletons, they very much need the stable and in line parameters just the same.

capture · 06/30/2008, 08:24 PM

thanks flyyyguy.
so no one keeps these levels in check? or is everyone else so good at it they don't feel the need to chime in?

Lotus99 · 06/30/2008, 09:26 PM

I try to keep my alk and calcium in check. I try to keep alk. at 9 dKH and calcium at 400 or more. I've been having swings in my tank. First alk was always low, now calcium seems low. Adding magnesium helped with the alk.

The tank is 18 months old, but I guess its needs keep changing. I add two-part as necessary.

650-IS350 · 06/30/2008, 10:46 PM

Anytime my zoa's look like SHYT' , its usually the Alk, pH and Cal are off wack.

capture · 07/01/2008, 04:56 AM

what are all of you using to get these back in check? Kalkwasser, buffer, what?

MUCHO REEF · 07/04/2008, 06:12 AM

Hey Capture, not sure why no ones replying to this, it's a great question.

1. How do you go about keeping this important chemical balance in your tank?

I have been using 2 part solution for so many years I have lost count. It sets and keeps everything in check. It's quick, simple and easy.

2. How large is your tank, what's in it?

75 gallon with zoanthids, palythoas and Floridian and Caribbean mushrooms.

3. Where do you tend to keep these levels (high, low, right on)?

Right on, right on, right on

4. Have any of these levels had a big effect on your zoanthids in particular?

Everyone seems to shoot for zero nitrates and I strongly disagree with this. I have actual seen better growth at 5 to 6 mg/L than I have at 0 mg/L. I know of countless reefers who have had the same results.

5. By keeping these levels where they should be, did your zoas/palys show better results?

I would say favorable results via growth.

6. Did you make tweaks to keep your zoas happy?

Nothing in a captive system is ever kept completely constant in my opinion. The goal should be very marginal/negligible fluctuations. This is always my goal. Tweaking should be done as needed with everything in a captive system if we want to maintain longevity with our system. Consumption/uptake of one thing this week, may or may not be the same next week. This is why weekly test has played such an important role in my system year after year.

7. With the increased numbers of reefers entering the hobby at the nano level, how could you help these nano reefers keep these levels inline with where they should be? These small tanks are much less stable than large tanks, that's why I ask.

The first thing I would say to a newbie is this. Spend as much time as possible reading before you buy a single piece of equipment. A reef tanks is like a little child, it must be watched, monitored, cared for and maintained. It can become sick, internal parts can fail and it requires attention and sometimes at the most inopportune time.

I believe in reading, reading and more reading. If one reads, reefing can and will become second nature. Your nano reef will give you what you give it. Knowledge, reading, asking questions, buying a few good books will all help the nano newbie keep his/her nano and those parameters in check on a daily bases. One caveat to this, nanos need even more attention in my opinion as it relates to keeping parameters in check. Large reef tanks affords one a greater margin of error in the event of a mistake, die off, heat issue or parameter spike. A spike in ammonia in a 75 gallon tank is not as serious as a spike in an 8 gallon nano. Again, knowledge is the key that opens the doors of success in reefing. Sorry for the long reply, but that's just me Capture.

Mucho Reef

jjmcat · 07/04/2008, 01:30 PM

I use to have to always keep adding baking soda ,calc,and epson salts to keep all my parms in check.Ever since I switched salts and keep up with my water changes I only check them once a month or so.My tank is primarily SPS and LPS corals.I use to be a zoa junkie but I was tired of them melting away.This was the final straw that broke the camels back when I lost this entire rock.

I am now up to 8 different morphs of zoas and palys starting the addiction all over again.Thanks Capture for starting this thread as I do think its very impotant to keep to keep all your parameters in check.
Calc-450
Alk-3.5 megs
Mag-1350
Ph 8.2

MUCHO REEF · 09/20/2008, 08:07 AM

This thread died much to soon.

650-IS350 · 09/20/2008, 09:11 AM

Yes, totally agree mucho. These thread and the parameters talked about is VERY crucial to zoa health, growth and longevity.

IridescentLily · 09/20/2008, 11:15 AM

Now this is a interesting, valuable thread. I'd love to see more experienced zoanthid keepers post about their Ca, Mg, pH, Alkalinity and what works best with their zoas.

IridescentLily · 09/20/2008, 12:09 PM

I've been reading about magnesium lately.
Am I understanding correctly that magnesium helps with alkalinity?
How else does magnesium help?
Can anyone explain how magnesium has helped or hindered your zoanthids, or their growth?

Thanks much.

MUCHO REEF · 09/20/2008, 12:22 PM

Quote:

Originally posted by 650-IS350
Yes, totally agree mucho. These thread and the parameters talked about is VERY crucial to zoa health, growth and longevity.

I hear you you 650-IS350. I really miss these types of discussions. There is so much to be shared and gained from verbal/written exchange. Discussing these and other like topics will go a long way when trouble arises and you aren't sure what the problem could be. Parameters are the first place to start when time is of the essence and your corals are declining rapidly. Discussions and sharing of personal tank information a proactive means helping by simply sharing.

Mucho Reef

seapug · 09/20/2008, 01:10 PM

I'm a firm believer in keeping all your params in line, regardless of what kind of corals you keep. Yes, zoas a tolerate poorer conditions, but you can't argue they are "better" in crappy water. Plus, keeping things in line makes for a generally healthier environment which improves the overall appearance of a tank.

That said, I've ALWAYS battled low Alkalinity and Magnesium in my tank for some reason. Calcium is always on the high side so that's never been a problem. I do dose Kalkwasser from time to time but find I need to do frequent baking soda supplements for the Alkalinity. I've poured gallons of Tech-M and Reef Magnesium supplements in the tank and can never get it above 1100.

I recently tested my Nitrates for the first time in about 6 months and found them hovering around 40. Yikes! Water changes haven't seemed to bring them down so I've been reading up on the Vodka method. Probably going to give that a try starting this week. Nothing seems to be suffering at that level, but I still don't like it.

elkinsda · 09/21/2008, 10:01 AM

So whats the secret to keeping zoanthids? I still have melt downs occasionally. But i swear my parameters are still running the same as usual.

I thought my melt downs where caused by my leathers mucus sheddings, but i have since move those into another tank and i still have melts once in awhile.

Is 8dkh bad for zoanthids? i keep my dkh level up around 9-10

-Derek

650-IS350 · 09/21/2008, 12:20 PM

I try to keep mine at 10dkh.

seapug. I thought that if your calcium is low, then your alk and pH are also in the lower range. as well as the MAG. These are all closely related as much as some folks don't think.

When I had zoas looking like crap, even when using other tester ( they should all was in spec ) but when I used a way better tester, Elos, it showed my Cal, pH and Mag were really lower than what my other test kits originally showed.

seapug · 09/21/2008, 09:25 PM

I try to keep mine around 10 dkh as well. 650-IS350, I have a hard time keeping my calcium below 475-500. I think that's the reason I battle alkalinity all the time. Bringing my alkalinity up brings the calcium down because it makes it more available for the skeleton building corals to utilize. It's very true-- calcium, alkalinity and magnesium levels are all related. I need to figure out a formula for supplementation that will maintain the numbers I'm shooting for...I just haven't figured out what that is yet!

BTW, I've started a Vodka dosing routine on my tank. I hadn't tested nitrates in my tank for a long time, but recently had a powerhead come loose and blow out part of the DSB in the back corner of the tank so I decided to test and found them pretty high. That may have something to do with my alkalinity problems. It'll be interesting to see if the method works for me and has an effect on my Zoas. I'm using the method outlined here:
http://www.reefkeeping.com/issues/20...nftt/index.php

650-IS350 · 09/22/2008, 07:16 AM

Isn't Vodka usage more for SPS?

I take it those soft corals you have also consume a LOT of calcium? Cause I've heard soft corals like kenya trees are like calcium sponges just like Monti Caps are too SPS.

seapug · 09/22/2008, 08:18 AM

Vodka dosage is for Nitrate and Phosphate reduction. It can improve colors and growth in all types of corals. That would be great if it did that, but I'm doing it primarily for nitrate reduction.

IridescentLily · 09/22/2008, 09:02 AM

I can't wait to see how your SPS does with the dosing, as well as your Zoanthids Seapug.
Please let us know how it goes.

650-IS350 · 09/22/2008, 10:36 AM

SeaPug.

Me personally as much as I preach to ensure parameters are in check. I don't check as much or anymore. I use my xenia and zoanthids as indicators to my tank parameters. Plus with weekly to bi-weekly WC's, I don't bother anymore

seapug · 09/22/2008, 08:10 PM

Yeah, I do weekly water changes and periodically check my alkalinity (been doing it more lately though). It keeps things generally acceptable, but I did a nitrate test for the first time in almost a year last week and noticed it was a bit high, so I'm starting the vodka routine (very carefully) so see if I notice any improvements over the next month. Day 3 and everything still looks the same. Tomorrow I step up to the Phase 2: The Double Dose.

IridescentLily · 09/22/2008, 09:00 PM

*bites fingernails*
Thanks for the update Seapug.

z's_N_p's · 09/23/2008, 12:19 PM

very good read.... thanks for posting this... it's good to be reminded every so often...

Merfin70 · 09/24/2008, 08:55 PM

Agreed, this is great for us new folks. I keep a fair number of Acans so I've been boosting my Mag recently. Probably around 1,400 and I've noticed that my zoas and palys seem a little happier and more colorful. I'm sure this is in part due to Ca and Alk being more stable as well. I dose a 2-Part to keep my levels in line as my tank seems to suck Alk and Ca even with the high Mag levels and a mostly LPS/Zoa tank. I can definately tell when my Alk is low as the Zoas get PO'ed at me and the Acans shrink.

I don't seem to get anywhere near the growth that others report but my tank is new and honestly, since its small, I don't need things growing like weeds on me.

06/30/2008, 08:50 AM	#1
capture Registered Member Join Date: Jul 2003 Location: CT Posts: 678	Ca, Mg, pH, Alkalinity & your Zoas Although our favorite corals don't require Ca & Mg to grow skeletons like SPS and LPS do, these parameters are integral in maintaining a healthy, thriving reef. Not to mention their balance and affect on pH and Alkalinity as well. How do you go about keeping this important chemical balance in your tank? How large is your tank, what's in it? Where do you tend to keep these levels (high, low, right on)? Have any of these levels had a big effect on your zoanthids in particular? By keeping these levels where they should be, did your zoas/palys show better results? Worse? Did you make tweaks to keep your zoas happy? With the increased numbers of reefers entering the hobby at the nano level, how could you help these nano reefers keep these levels inline with where they should be? These small tanks are much less stable than large tanks, that's why I ask. Feel free to contribute as you see fit.

06/30/2008, 01:07 PM	#2
flyyyguy King of the white corals Join Date: Jun 2006 Posts: 5,239	I will just add that low alk can be a huge culprit in allowing polyps to do the "meltdowns" we all know and love. Like capture said, while polyps may not need maintained levels of alk, calcium and mag to build skeletons, they very much need the stable and in line parameters just the same. __________________ I like holding hands, snuggling, and long walks on the beach

06/30/2008, 09:26 PM	#4
Lotus99 Registered Member Join Date: Oct 2006 Location: Southern California Posts: 1,398	I try to keep my alk and calcium in check. I try to keep alk. at 9 dKH and calcium at 400 or more. I've been having swings in my tank. First alk was always low, now calcium seems low. Adding magnesium helped with the alk. The tank is 18 months old, but I guess its needs keep changing. I add two-part as necessary. __________________ "So long, and thanks for all the fish" Current Tank Info: 125g reef, gobies, cardinals, softies and LPS; 36g Neo Nano tank; 10+ FW tanks

06/30/2008, 10:46 PM	#5
650-IS350 Registered Member Join Date: Nov 2004 Location: Bay Area Posts: 14,555	Anytime my zoa's look like SHYT' , its usually the Alk, pH and Cal are off wack. __________________ * RETIRED FROM REEFING * Just enjoying the box of water from afar

07/04/2008, 06:12 AM	#7
MUCHO REEF Registered Member. Join Date: Feb 2003 Location: Michigan Posts: 4,682	Hey Capture, not sure why no ones replying to this, it's a great question. 1. How do you go about keeping this important chemical balance in your tank? I have been using 2 part solution for so many years I have lost count. It sets and keeps everything in check. It's quick, simple and easy. 2. How large is your tank, what's in it? 75 gallon with zoanthids, palythoas and Floridian and Caribbean mushrooms. 3. Where do you tend to keep these levels (high, low, right on)? Right on, right on, right on 4. Have any of these levels had a big effect on your zoanthids in particular? Everyone seems to shoot for zero nitrates and I strongly disagree with this. I have actual seen better growth at 5 to 6 mg/L than I have at 0 mg/L. I know of countless reefers who have had the same results. 5. By keeping these levels where they should be, did your zoas/palys show better results? I would say favorable results via growth. 6. Did you make tweaks to keep your zoas happy? Nothing in a captive system is ever kept completely constant in my opinion. The goal should be very marginal/negligible fluctuations. This is always my goal. Tweaking should be done as needed with everything in a captive system if we want to maintain longevity with our system. Consumption/uptake of one thing this week, may or may not be the same next week. This is why weekly test has played such an important role in my system year after year. 7. With the increased numbers of reefers entering the hobby at the nano level, how could you help these nano reefers keep these levels inline with where they should be? These small tanks are much less stable than large tanks, that's why I ask. The first thing I would say to a newbie is this. Spend as much time as possible reading before you buy a single piece of equipment. A reef tanks is like a little child, it must be watched, monitored, cared for and maintained. It can become sick, internal parts can fail and it requires attention and sometimes at the most inopportune time. I believe in reading, reading and more reading. If one reads, reefing can and will become second nature. Your nano reef will give you what you give it. Knowledge, reading, asking questions, buying a few good books will all help the nano newbie keep his/her nano and those parameters in check on a daily bases. One caveat to this, nanos need even more attention in my opinion as it relates to keeping parameters in check. Large reef tanks affords one a greater margin of error in the event of a mistake, die off, heat issue or parameter spike. A spike in ammonia in a 75 gallon tank is not as serious as a spike in an 8 gallon nano. Again, knowledge is the key that opens the doors of success in reefing. Sorry for the long reply, but that's just me Capture. Mucho Reef __________________ Anyone can build a reef.....the greater challenge......is to grow one. Current Tank Info: 70 gallon zoanthid, Palythoa and Mushroom Reef.

06/30/2008, 08:24 PM	#3
capture Registered Member Join Date: Jul 2003 Location: CT Posts: 678	thanks flyyyguy. so no one keeps these levels in check? or is everyone else so good at it they don't feel the need to chime in?

07/01/2008, 04:56 AM	#6
capture Registered Member Join Date: Jul 2003 Location: CT Posts: 678	what are all of you using to get these back in check? Kalkwasser, buffer, what?

07/04/2008, 01:30 PM	#8
jjmcat Registered Member Join Date: Jan 2005 Location: Tulsa Posts: 4,249	I use to have to always keep adding baking soda ,calc,and epson salts to keep all my parms in check.Ever since I switched salts and keep up with my water changes I only check them once a month or so.My tank is primarily SPS and LPS corals.I use to be a zoa junkie but I was tired of them melting away.This was the final straw that broke the camels back when I lost this entire rock. I am now up to 8 different morphs of zoas and palys starting the addiction all over again.Thanks Capture for starting this thread as I do think its very impotant to keep to keep all your parameters in check. Calc-450 Alk-3.5 megs Mag-1350 Ph 8.2 __________________ Oklahoma Marine and Aquarium Society Support your LFS and your local club. Jarrod Lee Current Tank Info: 110 reef with a 55 gallon sump,3 metal halides

09/20/2008, 08:07 AM	#9
MUCHO REEF Registered Member. Join Date: Feb 2003 Location: Michigan Posts: 4,682	This thread died much to soon. __________________ Anyone can build a reef.....the greater challenge......is to grow one. Current Tank Info: 70 gallon zoanthid, Palythoa and Mushroom Reef.

09/20/2008, 09:11 AM	#10
650-IS350 Registered Member Join Date: Nov 2004 Location: Bay Area Posts: 14,555	Yes, totally agree mucho. These thread and the parameters talked about is VERY crucial to zoa health, growth and longevity. __________________ * RETIRED FROM REEFING * Just enjoying the box of water from afar

09/20/2008, 11:15 AM	#11
IridescentLily Editor-Reefkeeping mag Join Date: May 2008 Location: Albuquerque, New Mexico Posts: 3,858 Blog Entries: 5	Now this is a interesting, valuable thread. I'd love to see more experienced zoanthid keepers post about their Ca, Mg, pH, Alkalinity and what works best with their zoas. __________________ ~April Editor-Reefkeeping Magazine

09/20/2008, 12:09 PM	#12
IridescentLily Editor-Reefkeeping mag Join Date: May 2008 Location: Albuquerque, New Mexico Posts: 3,858 Blog Entries: 5	I've been reading about magnesium lately. Am I understanding correctly that magnesium helps with alkalinity? How else does magnesium help? Can anyone explain how magnesium has helped or hindered your zoanthids, or their growth? Thanks much. __________________ ~April Editor-Reefkeeping Magazine

09/20/2008, 01:10 PM	#14
seapug Registered Member Join Date: Dec 2006 Location: 4980 ft. Posts: 7,954 Blog Entries: 1	I'm a firm believer in keeping all your params in line, regardless of what kind of corals you keep. Yes, zoas a tolerate poorer conditions, but you can't argue they are "better" in crappy water. Plus, keeping things in line makes for a generally healthier environment which improves the overall appearance of a tank. That said, I've ALWAYS battled low Alkalinity and Magnesium in my tank for some reason. Calcium is always on the high side so that's never been a problem. I do dose Kalkwasser from time to time but find I need to do frequent baking soda supplements for the Alkalinity. I've poured gallons of Tech-M and Reef Magnesium supplements in the tank and can never get it above 1100. I recently tested my Nitrates for the first time in about 6 months and found them hovering around 40. Yikes! Water changes haven't seemed to bring them down so I've been reading up on the Vodka method. Probably going to give that a try starting this week. Nothing seems to be suffering at that level, but I still don't like it. __________________ insert clever saying here. Current Tank Info: 200 gallon custom Marineland DD peninsular tank. LPS dominated mixed reef. Previous 90 gallon mixed reef TOTM April 2009.

09/21/2008, 10:01 AM	#15
elkinsda Registered Member Join Date: Jun 2006 Location: Michigan Posts: 298	So whats the secret to keeping zoanthids? I still have melt downs occasionally. But i swear my parameters are still running the same as usual. I thought my melt downs where caused by my leathers mucus sheddings, but i have since move those into another tank and i still have melts once in awhile. Is 8dkh bad for zoanthids? i keep my dkh level up around 9-10 -Derek

09/21/2008, 12:20 PM	#16
650-IS350 Registered Member Join Date: Nov 2004 Location: Bay Area Posts: 14,555	I try to keep mine at 10dkh. seapug. I thought that if your calcium is low, then your alk and pH are also in the lower range. as well as the MAG. These are all closely related as much as some folks don't think. When I had zoas looking like crap, even when using other tester ( they should all was in spec ) but when I used a way better tester, Elos, it showed my Cal, pH and Mag were really lower than what my other test kits originally showed. __________________ * RETIRED FROM REEFING * Just enjoying the box of water from afar

09/21/2008, 09:25 PM	#17
seapug Registered Member Join Date: Dec 2006 Location: 4980 ft. Posts: 7,954 Blog Entries: 1	I try to keep mine around 10 dkh as well. 650-IS350, I have a hard time keeping my calcium below 475-500. I think that's the reason I battle alkalinity all the time. Bringing my alkalinity up brings the calcium down because it makes it more available for the skeleton building corals to utilize. It's very true-- calcium, alkalinity and magnesium levels are all related. I need to figure out a formula for supplementation that will maintain the numbers I'm shooting for...I just haven't figured out what that is yet! BTW, I've started a Vodka dosing routine on my tank. I hadn't tested nitrates in my tank for a long time, but recently had a powerhead come loose and blow out part of the DSB in the back corner of the tank so I decided to test and found them pretty high. That may have something to do with my alkalinity problems. It'll be interesting to see if the method works for me and has an effect on my Zoas. I'm using the method outlined here: http://www.reefkeeping.com/issues/20...nftt/index.php __________________ insert clever saying here. Current Tank Info: 200 gallon custom Marineland DD peninsular tank. LPS dominated mixed reef. Previous 90 gallon mixed reef TOTM April 2009. Last edited by seapug; 09/21/2008 at 09:50 PM.

09/22/2008, 07:16 AM	#18
650-IS350 Registered Member Join Date: Nov 2004 Location: Bay Area Posts: 14,555	Isn't Vodka usage more for SPS? I take it those soft corals you have also consume a LOT of calcium? Cause I've heard soft corals like kenya trees are like calcium sponges just like Monti Caps are too SPS. __________________ * RETIRED FROM REEFING * Just enjoying the box of water from afar

09/22/2008, 08:18 AM	#19
seapug Registered Member Join Date: Dec 2006 Location: 4980 ft. Posts: 7,954 Blog Entries: 1	Vodka dosage is for Nitrate and Phosphate reduction. It can improve colors and growth in all types of corals. That would be great if it did that, but I'm doing it primarily for nitrate reduction. __________________ insert clever saying here. Current Tank Info: 200 gallon custom Marineland DD peninsular tank. LPS dominated mixed reef. Previous 90 gallon mixed reef TOTM April 2009.

09/22/2008, 09:02 AM	#20
IridescentLily Editor-Reefkeeping mag Join Date: May 2008 Location: Albuquerque, New Mexico Posts: 3,858 Blog Entries: 5	I can't wait to see how your SPS does with the dosing, as well as your Zoanthids Seapug. Please let us know how it goes. __________________ ~April Editor-Reefkeeping Magazine

09/22/2008, 10:36 AM	#21
650-IS350 Registered Member Join Date: Nov 2004 Location: Bay Area Posts: 14,555	SeaPug. Me personally as much as I preach to ensure parameters are in check. I don't check as much or anymore. I use my xenia and zoanthids as indicators to my tank parameters. Plus with weekly to bi-weekly WC's, I don't bother anymore __________________ * RETIRED FROM REEFING * Just enjoying the box of water from afar

09/22/2008, 08:10 PM	#22
seapug Registered Member Join Date: Dec 2006 Location: 4980 ft. Posts: 7,954 Blog Entries: 1	Yeah, I do weekly water changes and periodically check my alkalinity (been doing it more lately though). It keeps things generally acceptable, but I did a nitrate test for the first time in almost a year last week and noticed it was a bit high, so I'm starting the vodka routine (very carefully) so see if I notice any improvements over the next month. Day 3 and everything still looks the same. Tomorrow I step up to the Phase 2: The Double Dose. __________________ insert clever saying here. Current Tank Info: 200 gallon custom Marineland DD peninsular tank. LPS dominated mixed reef. Previous 90 gallon mixed reef TOTM April 2009.

09/22/2008, 09:00 PM	#23
IridescentLily Editor-Reefkeeping mag Join Date: May 2008 Location: Albuquerque, New Mexico Posts: 3,858 Blog Entries: 5	bites fingernails Thanks for the update Seapug. __________________ ~April Editor-Reefkeeping Magazine

09/23/2008, 12:19 PM	#24
z's_N_p's Registered Member Join Date: May 2008 Posts: 327	very good read.... thanks for posting this... it's good to be reminded every so often...

09/24/2008, 08:55 PM	#25
Merfin70 Registered Member Join Date: Jun 2008 Location: Atlanta, GA Posts: 595 Blog Entries: 1	Agreed, this is great for us new folks. I keep a fair number of Acans so I've been boosting my Mag recently. Probably around 1,400 and I've noticed that my zoas and palys seem a little happier and more colorful. I'm sure this is in part due to Ca and Alk being more stable as well. I dose a 2-Part to keep my levels in line as my tank seems to suck Alk and Ca even with the high Mag levels and a mostly LPS/Zoa tank. I can definately tell when my Alk is low as the Zoas get PO'ed at me and the Acans shrink. I don't seem to get anywhere near the growth that others report but my tank is new and honestly, since its small, I don't need things growing like weeds on me.