PH and GFO/Carbon Reactor

[JakeLikesReefs]

Okay, so the pukani is still leaching PO4. My P04 was reading .07 today which is higher than I'd like. I received my new reactor today and followed BRS guidelines for carbon and GFO...i think it was a mistake as for the GFO because my PH proceeded to drop 2 points over about 6 hours (now reading 7.94). I retested phosphates at 0ppm and my alk went down to 8.3dkh which likely caused downward spike in ph. I have shut off the reactor. Any thoughts on this? Run less media? Only turn reactor on for an hour or 2 per day? Please let me know, need some help on this one.

Thanks,
Jake

 

[DLHDesign]

Hey Jake,
Would you mind providing the basics of your tank - size, general makeup (ex; mixed reef, softies, SPS-dominant, fowlr, etc.), how long the tank has been running, and how much carbon/GFO you added?

GFO will (should) reduce PO4. PO4 is an inhibitor to calcification (read: coral growth), so when it is removed - and assuming all else is good - then the result can be an uptake in other things - such as Alk. Ph drops along with the addition of GFO are also expected. This is a good uptake (more growth), but can cause you to adjust other things you are dosing in to maintain your levels. The reactor will also help clarify your water, which could also result in more growth. In short; nothing in a reef tank can be handled in isolation... ;-)

As to your specific fluctuations; we'll need to know the details above to know what best to do next. The BRS calculators can run a little bit heavy-handed, so it's conceivable that you may need less than it suggests.

 

[Randy Holmes-Farley]

GFO can induce precipitation of calcium carbonate on it and downstream of it, probably due to iron acting as a nucleating site for precipitation.

 

[JakeLikesReefs]

Hey Jake,
Would you mind providing the basics of your tank - size, general makeup (ex; mixed reef, softies, SPS-dominant, fowlr, etc.), how long the tank has been running, and how much carbon/GFO you added?

GFO will (should) reduce PO4. PO4 is an inhibitor to calcification (read: coral growth), so when it is removed - and assuming all else is good - then the result can be an uptake in other things - such as Alk. Ph drops along with the addition of GFO are also expected. This is a good uptake (more growth), but can cause you to adjust other things you are dosing in to maintain your levels. The reactor will also help clarify your water, which could also result in more growth. In short; nothing in a reef tank can be handled in isolation... ;-)

As to your specific fluctuations; we'll need to know the details above to know what best to do next. The BRS calculators can run a little bit heavy-handed, so it's conceivable that you may need less than it suggests.

Hello,

Thanks for the reply.

I have an IM25 Lagoon. It has been running for about 1.5 months and completed its cycle in 23 days. It is a mixed reef that has around 9 pieces of coral and 2 Clownfish currently populating the tank.

As far the carbon and GFO, I am using the ROX carbon from brs and the granular GFO from brs. I have 2 Table spoons of carbon and 4 Table spoons of GFO as per the BRS recommendations.

I was concerned with the rate at which my PH plummeted...should I just dose 2 part accordingly after checking Alk and Calcium? After turning the reactor off last night the PH bottomed out at 7.9 and has since risen to 7.95.

Thanks,
Jake

 

[penguin_free]

Do you know what your Mg is at? Maybe Randy can shed some light on the hypothesis, but is it possible low Mg might exaggerate the effect of the additional neucleating sites the gfo provides? Is your Ca dropping like alk is?

If that's true, then maybe bringing Mg up could help stabilize the alk anf pH.

 

[JakeLikesReefs]

Do you know what your Mg is at? Maybe Randy can shed some light on the hypothesis, but is it possible low Mg might exaggerate the effect of the additional neucleating sites the gfo provides? Is your Ca dropping like alk is?

I don't know yet, but will test later today. I didn't suspect my MG would be low because the tank being so new with frequent water changes using Red Sea coral pro salt.

Thanks,
Jake

 

[Randy Holmes-Farley]

I don't know yet, but will test later today. I didn't suspect my MG would be low because the tank being so new with frequent water changes using Red Sea coral pro salt.

Thanks,
Jake

Given that description, the magnesium is likely fine.

 

[JakeLikesReefs]

Given that description, the magnesium is likely fine.

Any thoughts as it pertains to recommended dose for my tank? Actual water volume is around 17 gallons.

Thanks,
Jake

 

[Randy Holmes-Farley]

What alk level do want to maintain?

 

[JakeLikesReefs]

Well, I'm not upset with the current level of 8.3, I think sticking around this level would be ideal. I don't want to be at exactly 8.0.

The main concern is the PH. Do I assume it will stabilize itself over time? Also, the reactor is currently off, id like to keep the current alk while running the reactor.

Thanks,
Jake

 

[Randy Holmes-Farley]

Well, I'm not upset with the current level of 8.3, I think sticking around this level would be ideal. I don't want to be at exactly 8.0.

The main concern is the PH. Do I assume it will stabilize itself over time? Also, the reactor is currently off, id like to keep the current alk while running the reactor.

Thanks,
Jake

pH isn't generally best addressed by dosing, although dosing the right thing WHEN you need alkalinity can help raise pH.

When alk drops below 8 dKH, use a calculator to figure the dose to get back to 8 dKH, and dose the same volume of calcium.

Then watch again and see how long it takes to drop again and dose again as needed. Soon you will develop a clear amount that seems to be needed.

This discuss pH:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

 

[JakeLikesReefs]

pH isn't generally best addressed by dosing, although dosing the right thing WHEN you need alkalinity can help raise pH.

When alk drops below 8 dKH, use a calculator to figure the dose to get back to 8 dKH, and dose the same volume of calcium.

Then watch again and see how long it takes to drop again and dose again as needed. Soon you will develop a clear amount that seems to be needed.

This discuss pH:

pH And The Reef Aquarium
http://www.reefedition.com/ph-and-the-reef-aquarium/

I appreciate the detailed response

I am familiar with dosing 2 part as it pertains to keeping stable cal alk and mag, but my greater concern or question is regarding the reactor and how much media to use. Any thoughts on that subject? I want to be able to run my reactor 24/7 without the need to worry about my PH and Alk plummeting.

Thanks,
Jake

 

[Randy Holmes-Farley]

pH will not be any sort of ongoing issue from using GFO, whether it was now or was just coincidence.

You can't readily distinguish demand for abiotic precipitation from coral uptake in any reef tank, so it just ups the need for the two part a bit.

 

[JakeLikesReefs]

So how do you suggest going about starting the reactor back up? Just monitor Dkh for a few hours and dose accordingly? I'm assuming that based on your comments the rapid depletion of alk and thereby ph will subside eventually?

Thanks,
Jake

 

[Randy Holmes-Farley]

So how do you suggest going about starting the reactor back up? Just monitor Dkh for a few hours and dose accordingly? I'm assuming that based on your comments the rapid depletion of alk and thereby ph will subside eventually?

Thanks,
Jake

I'd start it up and measure alk the next day. Many of us (myself included) use GFO and there is not any big problem with maintaining alk or pH when using it.

 

[JakeLikesReefs]

I'd start it up and measure alk the next day. Many of us (myself included) use GFO and there is not any big problem with maintaining alk or pH when using it.

If I notice a downward swing in PH again, when do I decide to shut it off?

Thanks,
Jake

 

[JakeLikesReefs]

I turned my reactor on about 45 minutes ago, so far no changes in PH or ORP as noted last time. PH is holding at 8.06 (after climbing back from last night's crazy drop). Will continue to update as I test alk cal and mag later today.

Thanks,
Jake

 

[JakeLikesReefs]

Update:

First, thanks to all who have responded...truly.

Tank parameters after dosing today:

Ph - 8.27
Cal - 455
Alk - 8.9
Mag - 1275 (still low, was 1200...yikes)
P04 - 0.00 (don't have ultra low detection)

Reactor is going steady and I can finally get my frickin hands out of the tank and enjoy my slice of the ocean

Thanks,
Jake

 

[Randy Holmes-Farley]

Looks good.

Happy reefing.

 

[rkpetersen]

P04 - 0.00 (don't have ultra low detection)

Reactor is going steady and I can finally get my frickin hands out of the tank and enjoy my slice of the ocean

Thanks,
Jake

Jake, just another opinion here. Although your GFO really shouldn't be having much direct effect on pH, it is possible for it to cause your phosphate to be too low. Corals will often show signs of stress if there is absolutely no phosphate in the water. GFO is awesome stuff but also very powerful; if you use a sizable amount in a slow flowing reactor, it can literally strip all the phosphate from your system overnight. Use much less than the manufacturer recommends to start, like 1/4 or even less. Get a Hanna ULR phosphorus (not phosphate) colorimeter and use it weekly or more often. Don't hesitate to remove that GFO for awhile if you can't detect any phosphorus in your water.