Replacing GFO

ryecoon · Mar 23, 2014

How often do you guys replace the GFO in your reactor? is there a time frame, schedule or do you wait for the phosphates to creep up?

Daniel@R2R · Mar 23, 2014

I do it based on testing...when phosphates start to rise a little.

ryecoon · Mar 23, 2014

mdbannister said:
I do it based on testing...when phosphates start to rise a little.

What the average time frame? if you were to take a wild guess.

Clink51 · Mar 24, 2014

I have the same question. most testers dont show any actual rise in Phosphates. maybe its my fault for using the cheap old API test kits

EW_Fish · Mar 24, 2014

When you see increase in algae. Its going to very from tank to tank. Bio load & How many water changes you do and so on

ryecoon · Mar 24, 2014

i highly suggest using the IM mini max reactor for GFO. its awesome water has never been better. Easy to replace and compact. Reasonable price too. http://youtu.be/RCYRjlEh3PM

jservedio · Mar 24, 2014

Clink51 said:
I have the same question. most testers dont show any actual rise in Phosphates. maybe its my fault for using the cheap old API test kits

Yes, the API test kit is garbage. I wouldn't be surprised if it can't tell the difference between 0.05ppm and 0.25ppm. I keep my phosphate at 0.02-0.04ppm and change my GFO when it gets to 0.06ppm or I start to see algae. That is usually around 5 or 6 weeks. I use the Hanna HI-736 ULR checker which has a sensitivity of +/- 0.015ppm.

ryecoon · Mar 24, 2014

Where can i purchase that hanna checker besides online? i need it NOW lol

jservedio · Mar 24, 2014

ryecoon said:
Where can i purchase that hanna checker besides online? i need it NOW lol

I got mine from Amazon. Make sure you get the right one - you want the HI-736 ULR Phosphorus checker - not the HI-713.

Pappy · Mar 24, 2014

jservedio said:
I got mine from Amazon. Make sure you get the right one - you want the HI-736 ULR Phosphorus checker - not the HI-713.

Hey! I have the h713 and it works fantastic! And I don't have to convert ppb to ppm. they're the same reagents fyi also.

AJsTank · Mar 24, 2014

I just change mine on a monthly basis so I don't have to ever worry about it.

KoleTang · Mar 24, 2014

Quote from a member on local forum:

GFO:
Think about it like using duct tape to clean the lint off your pants. The lint sticks to the tape. Once every inch of the tape has lint sticking to it, no more lint sticks. GFO/Carbon works in a very similar way. Carbon has organics and particles stick to it, GFO picks up phosphates.

Why be careful with GFO? Any change in a reef tank that is fast, good or bad, can be devastating to corals. Why would one run GFO only a few hours a day? Because one figures that if his phosphates are high, running it for a few hours a day will only lower it so much and it will not be a shock to the system.

If you use 'less than the recommended amount' but keep the pump on 24/7, well, all you have done is run water through it until it cannot absorb any more phosphates. You haven't really bought yourself anything here as far as the speed of the phosphate decrease, you have just limited how far it will go down. If you put enough in the reactor to absorb every last phosphate in the tank running the pump 24/7 for the next 3 days and then the GFO will be used up, great. However, if you don't replace the GFO for 4 weeks, well then that is 25 days that the phosphates have to build up before you replace the GFO. Then, you put in the full amount and it starts all over, drops it to zero over a few days and then keeps it there slightly longer than the last time. You essentially put your tank on a yo yo where the route down to zero phosphates is fast and the route back up to higher phosphates is slow.

What to do? My advice is that when you start GFO, use the recommended amount, but only run it for a few hours a day, that way, your phosphates don't lower too fast. After a week, maybe you can change to 24/7. Some people complain about 'clogging' of the reactor, to which I say, switch to using half the recommended amount, but change it twice as often. Personally, I run a little more than half the recommended amount, I run it 4 hours in the morning and 4 hours in the evening and I replace it every 2 weeks religiously now.

Starting with less than the recommended amount could work if you intend to step it down, but it is harder to keep up with I think. You'd have to do something like 3 Tablespoons over 3 days and that lowers it from .70 to .60 and then is exhausted. Now, I will go with 4 tablespoons over 4 days and that lowers it from .60 to .45 so on and so forth. Then, if you forget to change it out after a few days, they start to go back up. For me, it is easier to put the reactor on a timer and just control how much water is going through the GFO. Up to the person, I guess. You for sure can't use half the recommended amount but still wait 4-6 weeks to change it out, that will absolutely not help ease into it, in my estimation.

ryecoon · Mar 24, 2014

If i add a timer on the GFO reactor wouldnt it still have an effect if its still in the water but not tumbling? its still in a high flow area.

KoleTang · Mar 24, 2014

ryecoon said:
If i add a timer on the GFO reactor wouldnt it still have an effect if its still in the water but not tumbling? its still in a high flow area.

If it's in a reactor that is off how is it in high flow?

ryecoon · Mar 24, 2014

its inside the sump and theres holes in the reactor so water passes thru the top. But i guess what i mean to say is, will the GFO still be active with water contact.

KoleTang · Mar 25, 2014

ryecoon said:
its inside the sump and theres holes in the reactor so water passes thru the top. But i guess what i mean to say is, will the GFO still be active with water contact.

If water is moving through it then it is still treating the water.

jservedio · Mar 25, 2014

Pappy said:
Hey! I have the h713 and it works fantastic! And I don't have to convert ppb to ppm. they're the same reagents fyi also.

Yours is only accurate to +/- 0.04ppm and mine is accurate to +/- 0.015ppm (5ppb of phosphorus) and they are the exact same price. There is a very big difference between the two. If they are the same price, why not get the one that is 2.6x more accurate? Is the convenience of not having to do 3 seconds of mental math really worth losing that resolution?

For me, the only use for the Hanna is knowing I am not going too low with my phosphates (since I'll have algae if they are too high) - I constantly read 0.00ppm on the HI-713 which is useless. PS - I own both of them and got the 713 by mistake first and it wasn't much more useful than my Salifert kit.