Most effective way to use GFO for phosphate reduction ?

[eskymick]

What is an effective technique using GFO to lower phosphates in a reef? I never used to have a problem, but now they hover around .08 ppm (Hanna pH Checker) in my reef, and I can't seem to get them down any lower.

Should I use more GFO and change it more often? Right now, I use 1.5 cups in a BRS reactor, and I change it weekly in my 135 gallon system. Being at .08 ppm, should I replace the media two or more times per week? Is there a typical guideline for GFO exchange?

I normally do a 10% weekly water change with RO/DI water. Last week, I did two 25% changes. Still ... at .08 ppm

I use use N/P bio pellets in a reactor, and nitrates are at .2 ppm. I get only a thin white film on the glass of the tank ... which I clean weekly. Am I keeping nitrate too low?

I've tried many times to keep chaeto in the sump. I can't keep it alive.

I feed well-rinsed mysis shrimp once or twice per day. Taking care not to overfeed. I do not use flake food.

I'm trying to get phosphates down to .03 ppm, but I just can't seem to get there. My SPS growth is non-existent.

What am I doing wrong .. or what more can I do?

[travismcgee]

i would check the ro/di water if that many water changes don't help

[Crossbow]

Using the BRS calculator you should use 2.11 cups of GFO (if you use granular) for a 135 gallon tank. I would try increasing the amount of GFO and slowing down the flow through the reactor for a longer exposure time.

[eskymick]

Using the BRS calculator you should use 2.11 cups of GFO (if you use granular) for a 135 gallon tank. I would try increasing the amount of GFO and slowing down the flow through the reactor for a longer exposure time.

If I remove the center sponge from the reactor, I can put 2+ cups in it. I'll do that.

BRS says that the GFO should be changed monthly. I've been changing it weekly without much success. Should I change the GFO media more often at a level of .08 ??

[Crossbow]

Try the larger amount first before changing the frequency. It is important that you slow down the flow to maximize the time that the water column flowing through the reactor is in contact with the GFO. Fight the good fight, you'll get there!

[eskymick]

It is important that you slow down the flow to maximize the time that the water column flowing through the reactor is in contact with the GFO.

I have it set so that there is just barely movement at the surface of the GFO in the reactor. Slower yet?

[chuckreef]

In wastewater treatment systems, the GFO exhibits very high rate of PO4adsorption initially and then it drops to almost proprotional to the PO4 level.
Changing it out every one to two days for a week or two is usally what it takes to get a significant drop in a polluted system. It is expensive initially, so if the PO4 source(s) has not been eliminated, it is not worth the money.
Once the PO4 is lowered and no new sources are added GFO may last two or three weeks to maintain low PO4.
IMO, generally a large water change with verified low PO4 artifical seawater followed by a week or so of intensive GFO use (I.e, frequent changout) is the best way to go.

[mayjong]

measure the po4 in your tank, then measure the po4 coming out of your gfo reactor, if the same, change the gfo

[shaggss]

+1 on above, test the water coming out of your reactor.

[eskymick]

Thanks for all the great advice. It opened my eyes to some possibilities that I had dismissed as "impossible".

Keeping in mind that my reef water tests at .08, I just now completed three different tests with my my Hanna Checker:

1. The output from my BRS GFO reactor: .04
2. The output from my RO/DI unit: .00
3. The RO/DI output water being stored in my Brute container (i.e. my top-off water): .20 (YIKES)

Now what?

[chuckreef]

1. The output from my BRS GFO reactor: .04
2. The output from my RO/DI unit: .00
3. The RO/DI output water being stored in my Brute container (i.e. my top-off water): .20 (YIKES)
Now what?

As stated above, eliminate the source first; >>> dump and rinse the brute and/or replace the brute, then fill the (new) top off container using your RO/DI unit. As long as the removal rate is greater than the influent rate, the PO4 will come down. If you want it to come down even faster (after eliminating the source - I.e., the top off system), then use more GFO and change it more frequently. Right now its at a 50% reduction rate (.04/.08). New GFO will probably give more like 90% removal - try it. (Don't be afraid to experiment a little with your reefing tools, such as GFO).

[bertoni]

That's a lot of phosphate for a Brute container with RO/DI in it. I might empty the container and clean it carefully with some vinegar, but I also wonder whether the measurement is accurate. I'm not sure how the phosphate would manage to get that high without something going into the container.

[eskymick]

I added a second reactor today ... with two cups of GFO. I'll leave both reactors runnning for as long as necessary.

I replaced the Brute with a glass tank. No more plastic for RO/DI storage.

[eskymick]

That's a lot of phosphate for a Brute container with RO/DI in it. I might empty the container and clean it carefully with some vinegar, but I also wonder whether the measurement is accurate. I'm not sure how the phosphate would manage to get that high without something going into the container.

That container was purchased new two years ago and has been used exclusively as a RO/DI storage container since that time.

[bertoni]

I'd also consider increasing the flow in the reactors. I think they're supposed to be fluidized, which means the media should be tumbling gently.

I'm not sure what's happening with the Brute container, but a lot of people use them without phosphate problems.

[Daimyo68]

Get the GFO to a slow "boil" on the surface inside the reactor. You don't want the entire contents "boiling" around. It will cause the GFO to break down early and possibly release P04 back into the system.

According to BRS - Reduce the flow through the reactor so the GFO barely tumbles on the surface. Do not allow the material to vigorously tumble

According to the Phosban Directions: Adjust the flow with the ball valve so that the PhosBan granules are tumbling slightly at the surface

To help prevent "channeling" through the media over time, I open the valve from the pump to completely tumble the media once a week, and then adjust back to a boil.

[eskymick]

All good advice. I never once considered that the source of my phosphate contamination was from my RO/DI storage container. What a relief to finally have a handle on it. By week's end, I'll be phosphate "free".

[chuckreef]

Was the Brute covered?
Normal dust can contribute PO4 over time, if it was not.

Also when a DI resin goes, often a lot of PO4 can be released relatively quickly. If your resin was spent/changed out recently, it could have contributed PO4 before you replaced it.

[eskymick]

Was the Brute covered?
Normal dust can contribute PO4 over time, if it was not.

Also when a DI resin goes, often a lot of PO4 can be released relatively quickly. If your resin was spent/changed out recently, it could have contributed PO4 before you replaced it.

Yes, the Brute has always been covered.

The DI resin is due to be replaced in a few months so it's not new. The output from the unit reads zero TDS and tests at zero phosphates.

[d0ughb0y]

measure the po4 in your tank, then measure the po4 coming out of your gfo reactor, if the same, change the gfo

this is the right way to know when to change the gfo if you have a meter.
you can see gfo can be completely exhausted overnight if you start out with high phosphate. as someone mentioned, you may have to change it every day at the beginning. for maintenance (when po4 is zero), you can use half of what brs tells you to use. if you look at gfo instructions from other sources, it is about half of what brs tells you to use. there is absolutely no harm (except to your wallet) to using more than what is necessary.