How often to replace GFO?

[Jeannine]

I just started running GFO in a reactor. I have struggled with high phosphates pretty much (0.3-0.5 per hanna). Tank is about 2 yrs old now. I really want to get my few corals growing instead of struggling and eventually add some. Also my clean up crew's not able to keep up with the hair algae. Anyway, I started the GFO on 12 /29. In 24 hrs phosphates went from 0.4 to 0.21. The next day, Jan 1st, they were 0.15! I was so excited....till I just tested today and I'm back to 0.3! Surely I don't need to change it already... my weekly water change day is Thursday, so it's still a couple of days away.

 

[Randy Holmes-Farley]

I just started running GFO in a reactor. I have struggled with high phosphates pretty much (0.3-0.5 per hanna). Tank is about 2 yrs old now. I really want to get my few corals growing instead of struggling and eventually add some. Also my clean up crew's not able to keep up with the hair algae. Anyway, I started the GFO on 12 /29. In 24 hrs phosphates went from 0.4 to 0.21. The next day, Jan 1st, they were 0.15! I was so excited....till I just tested today and I'm back to 0.3! Surely I don't need to change it already... my weekly water change day is Thursday, so it's still a couple of days away.

The higher phosphate is, and the faster water is passed through the GFO, the faster it depletes.

It could be depleted, but you can verify by measuring phosphate in the effluent from it to see if it is lower than the tank or not.

What corals are struggling?

 

[Jeannine]

I don't have too much. Some zoas, 2 duncans, a candy cane and 2 gorgonians. I had a few acans that eventually died. They don't look bad, just aren't really growing

 

[Jeannine]

I don't have too much. Some zoas, 2 duncans, a candy cane and 2 gorgonians. I had a few acans that eventually died. They don't look bad, just aren't really growing

The higher phosphate is, and the faster water is passed through the GFO, the faster it depletes.

It could be depleted, but you can verify by measuring phosphate in the effluent from it to see if it is lower than the tank or not.

What corals are struggling?

I tested the tank water today and PO4 was down to 0.18. Not sure why it was 0.3 yesterday? I checked the effluent from the reactor to compare as you suggested and got 0.10. I guess I just need to be patient as it seems to be working. I've never had phosphate this low.

 

[Randy Holmes-Farley]

There are many reasons corals do not thrive, including lots of chemical and nonchemical reasons.

I would not bet on the phosphate being an issue.

Have you measured nitrate?

An icp test of the water from a good icp company might be a good start.

 

[Jeannine]

My nitrates run in the 20s typically. Up to 32 today, but time for weekly water change tomorrow. Alkalinity 8.3, calcium 435, magnesium 1390, S.G 1.026, pH 8.2. Temp 77.8. I have a pair of clowns, a fox face, a mimic tang, a benggai cardinal, and 4 pj cardinals. One fire shrimp and 2 BTAs (it split). My tank is 85 gal. I feed a pinch of flakes in am, and a cube of frozen in the pm. I cut out the flake completely and it never helped bring anything down and the foxface got really skinny. So I added it back and I started feeding a little nori, a few times a week. I feed reef roids 2-3 x a month. I started dosing vodka last May, and have coninued.

 

[Randy Holmes-Farley]

I don't detect any reason in that post for failure of corals to thrive. I'd look for other explanations.

 

[Jeannine]

Ok, thanks. I'll see about icp testing. Can you recommend?

 

[Randy Holmes-Farley]

Ok, thanks. I'll see about icp testing. Can you recommend?

Oceamo would be my top choice.

 

[yanetterer]

Oceamo would be my top choice.

Is there a reason you suggest them over say, ATI?

Are there other US distributors besides aquabiomics? The Oceamo link on their site no longer works.

 

[areefer01]

Is there a reason you suggest them over say, ATI?

Are there other US distributors besides aquabiomics? The Oceamo link on their site no longer works.

There are a few different ones that collect via the US and distribute. Triton may have something local in the US now but don't hold me to that. There is a thread here somewhere along the lines of hobby grade test kits perform better than.... Little bit of talk in it about ICP among other things.

Having said that as a fellow hobbyist I have used both Oceanmo and ATI with consistent results. I only use ATI now and send in about three samples a year. I collect the sample the same way, same time of day within a few minutes, about the same time of week, and get results within 7 to 9 days. I'm on the West coast. I stayed with ATI because I like their support and I have more results with them which makes comparing across them better. Trending.

 

[Randy Holmes-Farley]

Is there a reason you suggest them over say, ATI?

Are there other US distributors besides aquabiomics? The Oceamo link on their site no longer works.

I have more confidence in the principle person behind that operation than others based on personal interactions here. I do not know that ATI is any worse, I just do not have the same level of knowledge of them.

 

[jda]

Oceamo is also the only company who is transparent about what and how the test. Some places just will not tell you if they have an employee using the same test kits that you do on compounds... which some of them do.

As for the GFO, the stuff usually exhausts in a powered reactor in a day. Since your reading went back up again, it is exhausted and can no longer bid as the aragonite is unbinding po4. I would use a smaller amount and change it daily. You want the water po4 level to say more linear instead of bouncing up and down - the lowering is not an issue, but the bouncing can be.

As for po4 and corals, there are some corals that will not like po4 of .3, but also many more that will not care at all. Without knowing the types, it is hard to say. There is no harm in lowering the po4 but there is also no harm in just letting things play out if everything else is OK and just living with the corals that do well at your levels.

Reef Roids are known to raise po4 significantly. I doubt that you have any corals that can really use them, unless you have some NPS, so if you want to po4 from rising, then you can consider stopping them.

 

[threebuoys]

Sorry to horn in on this thread.... the responses caught my attention.

Reef Roids are known to raise po4 significantly. I doubt that you have any corals that can really use them, unless you have some NPS, so if you want to po4 from rising, then you can consider stopping them.

Are other powdered coral foods less likely to raise po4 than reef roids? What do you consider to be good choices?

I use a gfo reactor for my 125-gallon tank. I fill the canister 3/4 full and let it run indefinitely until I measure po4 above about .15. Usually, it takes weeks if not months for that to happen. Of course, I may not be feeding as much Reef Roids or other coral foods that would raise po4 faster. I'm a little inconsistent in frequency and I use several other powders alternately. Sounds like I might be able to better control po4 if I'm a bit more systematic in my approach.

 

[jda]

I am not the guy to ask. I have tried many kinds of coral food over the decades and I do not think that any of them do anything. Just ample fish waste. Sorry that I was not any more help.

When using a huge amount of po4, you usually strip the water really clean and then the level rises again as the aragonite releases. This up/down can be bad for some corals while others might not care at all.

GFO can get covered in organics and be less useful - another reason to use less and change it more often. GAC does the same thing.

 

[areefer01]

GFO is more maintenance as it relates to preparation and cleanup. It is messy. Especially as you work through the management of phosphate and rebound if substrate and/or rocks are binding it.

 

[Uncle99]

Some believe that too much phosphate inhibits growth and dulls colours in some Stoney corals.

From the pics I see posted, doesn’t seem to ring true.

What exactly “too much” is IDK, but, I’m currently reducing my phosphate from 0.25ppm ( 2 years) to 0.05, so over the next 6 months, we see if there’s any difference running at that level and my Nitrate from 15ppm to 2ppm.

 

[radiata]

Oceamo would be my top choice.

Hi Randy!

Are the Oceamo sampling test kits available in the USA? The best I can find is a reference to Humble Fish being an "Oceamo Partner", but I see no kits available on their site.

I think I can live with the €67.90 cost of the kit, but a €100.00 delivery charge to the US is a bit on the painful side...

Thanks in advance,
Bob D.

​

 

[Miami Reef]

Hi Randy!

Are the Oceamo sampling test kits available in the USA? The best I can find is a reference to Humble Fish being an "Oceamo Partner", but I see no kits available on their site.

I think I can live with the €67.90 cost of the kit, but a €100.00 delivery charge to the US is a bit on the painful side...

Thanks in advance,
Bob D.

​

You can buy it from the Reef Moonshiner’s website. No, you don’t need to use their program to use the Oceamo ICP. I purchased it from RM and got my results from Oceamo

 

[radiata]

You can buy it from the Reef Moonshiner’s website. No, you don’t need to use their program to use the Oceamo ICP. I purchased it from RM and got my results from Oceamo

Thank you Randy!

I just ordered 2 tests from them. I'd never have made the Oceamo/Moonshiners connection without you!

Bob