New to GFO, have some questions

[Darth_Tater]

Hi all!

I wasn't sure if this should go here, the chemistry thread, or the DIY thread, but I've decided to try GFO in a DIY "reactor" and have some questions.

I've got a 40 breeder with a 20 long sump (total system volume about 50 gallons). I've got GHA growing like crazy. As in 6+ inches per week. I'm guessing the phosphate is coming out of my rock since I don't consider myself that heavy an over-feeder. My nitrates are undetectable. I've got 5 T5s about 9 inches above the tank. I have a very large skimmer for this size tank, it's an Eshopps but don't remember the specific model right now, but it's advertised for 200-ish gallons. Oh, and I've been doing 20 percent water changes twice a week for 2 months now with very little impact.

My setup will be this: a small old Eheim canister filter for the "reactor". I'll have an old Marineland Maxi-Jet 400 pushing water through it (the canister is going to sit in such a way that I won't be able to start a siphon so I can't use the internal pump). It's low flow for a container that size, so not sure I'll get much tumbling, but I ordered the high density GFO so hopefully it will work out.

So the questions:
How much GFO should I start out with?

Is it true using too much can cause more harm than good?

How often do I need to change it? I'm assuming this will depend on how high my phosphates are, which I don't know for sure because phosphate test kits are stupid (in my experience at least).

Thanks in advance for any input!

[scooter31707]

When I started using GFO, I started off with about 1/4 of what was recommend, then gradually worked up, if needed.

[Green Chromis]

:fish1: The amount you use should be on the container of the product you purchased. On the GFO I use, it depends on the water volume. Learn how to measure phosphates before you start using GFO, you need to know when the media is exhausted so you can replace it. Yes you can use to much GFO, just go by the instructions on the media container. It is very easy to use, and good luck with your system. :fish1:

[Darth_Tater]

Ah, I don't have the GFO yet, it's still in the mail.

So the way to tell when to change the media is when phosphates start rising again? I feel kinda stupid for thinking it was more complicated than that... I guess it's because I read that it will actually leach phosphates back into the water if you let it go too long. Ok, thanks for the feedback!

Can anyone recommend an easy to use phosphate test kit? I hate the API one and it's not very easy to detect low levels on it.

[anbosu]

Hanna sells a few good options. I'm not sure anything else gets low enough to really matter.

[Indymann99]

If you get the Hanna Phosphate checker make sure you get the ULTRA LOW model... I got the standard model and it always reads 0... :-(

[Reef Frog]

Remove as much GHA as you can by hand and siphon or filter and the resulting debris, plus remove excess material from the LR right before you bring the GFO on line. This will give you a good head start.

Saturated GFO shouldn't leak captured PO4 back into the water. But with very high levels it can become saturated very quickly, sometimes in only a couple of days. That's why testing is important and can even save $$ in the long run in a situation like yours. Meters are the way to go. Even the better chemical reagent tests can only distinguish down to about the .1ppm level, if that, and you most likely need to drive it down lower than that and keep it there. Otherwise it's just a guessing game & intuition. If you don't change the GFO soon enough in the initial stages,'the algae is likely to persist and even grow some more.

Once you enter the maintenance phase, changes needed become fewer over time and you can ease into a regular schedule without testing as much. In a canister filter, I'd use a slow flow through the mesh bag to maximize contact time, and pack it loosely so all particles get as much equal water exposure as possible. An up flow reactor can be had for under $50 and is much more efficient BTW. GL.

[fishgate]

The issue with being in a canister filter is you won't be able to see it tumble. I have a little fishies reactor and I add just GFO enough so it tumbles and gets good saturation. That is a little under 1/2 full with a 400gph power head feeding it. I have the pump in the first compartment of my sump and it pumps into the reactor and discharges in the middle chamber to make sure I don't short cycle the water through it. Too much GFO and it will clump up and not do much at all.

[eddiereefs]

What reef frog said.

[TangingOut]

Get a two little fishies reactor and a hanna ulr 736 meter. You won't regret it.

[Darth_Tater]

Thanks everyone for the input!

An up flow reactor can be had for under $50 and is much more efficient BTW. GL.

I'm aware of this, but that's $50 and my canister filter was free. If I'm not satisfied with results I'll probably get a reactor.

Get a hanna ulr 736 meter. You won't regret it.

Thanks, I'll probably end up getting one of these! Takes all the guesswork out of matching colors that look almost the same. And not much more than a liquid test kit.

[Darth_Tater]

Going to dig this up because I have another question. For those of you who suggested to skip the canister filter and go for a reactor you have the right to say "I told you so!" because that's exactly what I did.

I did buy the Hanna ULR meter. It seems to work great. I had the GFO installed for quite a while because the highest reading I got off the meter was 002. As in 002 PPT. Kind of annoying since the algae still seems quite happy which I guess means my rocks are leaching.

Anyways, here's the question: I replaced the GFO this weekend and when I tried to dump the old stuff out it became clear quickly that most of it was a solid mass that was hard as a rock. Also the sides of the reactor chamber were covered in a white film that was impossible to clean off. It was more like they plastic was dyed than a film. Is this normal? Could it have been caused by detritus getting into the reactor? Did I just leave it in for WAY too long?

Thanks in advance!

[3dees]

I tried gfo in a canister and it didn't really help. last week I set up a phosban reactor and I already see improvement.

[drummerboyevil]

I tried gfo in a canister and it didn't really help. last week I set up a phosban reactor and I already see improvement.

What was your phosphate before the GFO? A lot of time people thing that GFO didn't work, but what happening is that there is so much phosphate in the water column and in the substrate and rocks that the GFO is exhausted in hours and the level barely changes. Then they switch products thinking that the first one didn't work, but the second one has to work less to show a larger reduction.

GFO DEFINITELY removes phosphates.. it's just a matter of what your situation is as far as stores of phosphate goes. It gets to an equilibrium between rock/substrate and the water column very quickly.

[Hal]

How old is your tank? Most new tanks go through several stages of algae growth and death as the tank produces and uses up nutrients before it reaches An equilibrium. Think of it as an algae version of the ammonia/nitrite/nitrate cycle.

[Indymann99]

I have had great success with the BRS Dual GFO and Carbon system. Easy to change media and doesn't clog between the 1mo service interval.

I have very little to no algae in the DT (I don't care about the cyano in the sump)...

I change GFO and Carbon 1x per mo (now that my phos is under control).

https://youtu.be/se3usxkqYno

[buildinboats]

Anyways, here's the question: I replaced the GFO this weekend and when I tried to dump the old stuff out it became clear quickly that most of it was a solid mass that was hard as a rock. Also the sides of the reactor chamber were covered in a white film that was impossible to clean off. It was more like they plastic was dyed than a film. Is this normal? Could it have been caused by detritus getting into the reactor? Did I just leave it in for WAY too long?

Thanks in advance!

The precipitate on the sides of the canister is most likely calcium carbonate. I normally use a cake frosting knife to scrape this off, it does flake off fairly easily. If it's really a mess I use a very dilute solution of muriatic acid although a vinegar soak should work and be a bit safer.
The solid brick in your reactor is from not enough tumbling and not changing the GFO soon enough. It is a real PITA to get out!

[Steve175]

Yep: up flow reactor to allow visible tumbling is key. You will spend way more in wasted gfo than buying this early

[asharerin]

OP two dollars in 3% hydrogen peroxide will remove all of your GHA for you. Mix it 1 cup H202 per 2 gallons tank water in a 5 gallon bucket. Take each piece of rock and dip it it the bucket for 2-3 mins. GHA will be gone in 2 days. Stay on top of your parameters after that and it will not return. Once in the system the GHA needs less nutrients than your corals to survive. You can spend all kinds of money on chemicals and equipment to strip all of the nutrients out of your water to get rid of GHA but it will take months and starve your corals.

[Darth_Tater]

The precipitate on the sides of the canister is most likely calcium carbonate. I normally use a cake frosting knife to scrape this off, it does flake off fairly easily. If it's really a mess I use a very dilute solution of muriatic acid although a vinegar soak should work and be a bit safer.
The solid brick in your reactor is from not enough tumbling and not changing the GFO soon enough. It is a real PITA to get out!

Thanks for actually answering my question! I think I put too much in again this time around since there isn't much tumbling going on now. This "300 GPH" powerhead that comes with the BRS reactor is kind of disappointing.

OP two dollars in 3% hydrogen peroxide will remove all of your GHA for you. Mix it 1 cup H202 per 2 gallons tank water in a 5 gallon bucket. Take each piece of rock and dip it it the bucket for 2-3 mins. GHA will be gone in 2 days. Stay on top of your parameters after that and it will not return. Once in the system the GHA needs less nutrients than your corals to survive. You can spend all kinds of money on chemicals and equipment to strip all of the nutrients out of your water to get rid of GHA but it will take months and starve your corals.

Thanks for the suggestion, but like I've said before there is too much living on my rocks right now and I'm not going to nuke the tank. Plus the phosphate is coming from the rocks themselves so even if the algae DID go away it would come right back.

The GFO is the only thing I've spent money on to help control the algae so I don't know why you think I'm spending tons of money on "chemicals and equipment to strip all of the nutrients out of your water to get rid of GHA but it will take months and starve your corals."

I will just be patient and keep harvesting algae and when the phosphate finally stops leaching from the rocks the algae will go away :)