High Capacity GFO vs Regular

[ucdcrew]

I'm gonna buy a GFO reactor. The BRS one says it holds 2 cups of GFO. Their calculator says I need 2 cups of media for the water volume in my tank (I used entire volume of sump + display, not taking displacement into account). Is there any benefit to putting more GFO than is required into the reactor - say by using the high capacity?

 

[Reef Frog]

You can fit the same volume of high capacity as regular capacity in a reactor. The high capacity stuff just is going to last longer before becoming exhausted when compared to the regular stuff. HC also seems a little bit easier to wash out the fine dust before using than the regular type.

The HC is is heavier per unit of volume so this is probably why it can hold more phosphate than the regular type. I am basing this statements on observation rather than testing with a high precision meter.

For me both work well. If you find changing out the GFO to be a big chore you come to hate, HC is a good option. Higher absorbancy but higher cost.

 

[homer1475]

Also depends on how much your trying to take out of the water. Sometimes if your phosphates are real high, the HC stuff is just a waste of money.

In the beginning, I tried the HC stuff and found I was changing it at almost the same time as regular GFO. It did pull down my PO4 faster, but it also costs more. I personally would only use the HC stuff once your PO4 is under control and your only using it to maintain a certain level.

 

[TangingOut]

Most people use less than what the BRS calculator says, myself included, but you're wanting to use more without accounting for displacement?

Do you have a phosphate problem or just trying to maintain them? What's it currently testing at?

If you completely strip your water the corals may not be too happy.

 

[ucdcrew]

I think I have a phosphate problem - due to growth of GHA. Its testing 0 on API, but the growth is significant which I think is masking the level. I wrote this before I ordered the reactor - I was trying to figure out if the HC in a mini reactor would work for me. I ended up just buying the regular sized one - but did buy HC media.

Hopefully adding the GFO won't bother my coral too much as I get it dialed in. I'm new, so all I've got right now is 2 zoa colonies and a green hairy mushroom. I had a frogspawn, but it disappeared overnight. I heard they don't like phosphate. I'm thinking it was either phosphate or someone went on a murderous rampage. I'd only had it for a couple days, but it seemed to be doing okay. No tissue receding or secretions, all polyps out. Then one morning I woke up and it was a skeleton.

Other params:
Ammonia: 0
NitrIte: 0
NitrAte: 5
Calcium: 390
Alkalinity: ?? the number I have saved looks an order of magnitude off. Will retest.
Magnesium: 1560
SG: 1.026
Temp: 78.5
pH: fluctuates between 8.15 and 8.29

 

[jason2459]

Along with many of the points above you can regenerate HC GFO a lot more helping to reduce its cost greatly. TMZ on here has regenerated it up to 10 times. I've done 4 times now but there's plenty more times I can regenerate it. It's just waiting to be used again in a container.


Also, I would highly suggest a PO4 kit designed for our needs at the lowest ranges with high resolution. API is a fine brand but the PO4 kit from API is not made for the reefs we keep and much more useful for freshwater tanks. I would suggest the Elos Pro or the Hanna ULR 736 Checker.

 

[ucdcrew]

For the Hanna checkers - it says one is for phosphorus (ultra low range), and one is for phosphate. Just want to check to make sure the ULR one is the one I'm looking for.

 

[jason2459]

For the Hanna checkers - it says one is for phosphorus (ultra low range), and one is for phosphate. Just want to check to make sure the ULR one is the one I'm looking for.

Both the 713 low range and 736 ultra low range will do but I prefer the 736 as its slightly better and the price is the same. The 736 has higher resolution but as you noticed is for phosphorus in ppb but is easily converted to phosphates in ppm.

(ppb# * 3.066) / 1000 = ppm phosphates

The 713 has an accuracy of +/- .04 ppm. The 736 has an accuracy of +/- 5 ppb. When getting in to the lowest ranges that we normally target for at .03 ppm phosphates that could mater.

Here's a scenario I just was in the other week. I tested 6ppb on the 736 ULR but on the 713 low range Checker I got back 0.00ppm phosphates.

At 0.00 I could be anywhere between 0.00 and 0.04ppm phosphates on the 713.

At 6ppb phosphorus I would be between 1ppb or 11ppb.

Converted that
6ppb = 0.018ppm phosphates
1ppb = 0.003ppm
11ppb = 0.033ppm

So, that shows at the very low ranges we want to be in the 736 is more precise.

Review of PO4 kits including the above
http://www.reefcentral.com/forums/showthread.php?t=2540702

Suggested parameters
http://www.reefkeeping.com/issues/2004-05/rhf/index.php


Edit:
Looks like I tested 11ppb that day when testing 0.00ppm on the 713. It was a follow up test in another comparison thread I tested 6ppb. This is actually an even better example as the 713 may have someone deciding to dose phosphates because they deem they are PO4 limited and why their SPS look pale. But this comparison shows the 713 to be wrong and that there's plenty of phosphates in the water. Dosing more phosphates could lead to cyano or algae issues.

So, at 11ppb I could be between 6ppb or 16ppb.

Converted that ( still all with in that range of accuracy of the 713 at 0.00ppm)
11ppb = 0.033ppm
6ppb = 0.018ppm
16ppb = 0.049ppm

That's about as perfect a range you would want to be in. But the 713 could continuously read 0.00ppm leading to that dosing mentioned above.

 

[jason2459]

And to give the negatives of them is that they both have had issues with bad reagents in the past. Reagents and user errors are two things that I feel are the most common problems with any test kit for any parameter.

I personally have not had bad reagents with either the 713 or 736. I also try to limit inconsistencies by performing every test the same way every time. This goes for any kit. I've always had pretty consistent results with the 736.

Out of curiosity I went ahead and did a test with it tonight.

9ppb

(9ppb * 3.066) / 1000 = 0.028ppm phosphates

 

[downbeach]

You only need to use half as much of the HC than you do their regular granular. I've used both, and found that my system(190 net) required ~ 3 cups of the granular vs 1 1/2 cups of the HC, which would fit nicely in their regular sized reactor. Although more expensive, I would get better use from the HC, which in the long run was more economical. I would get ~ 7 to 8 weeks of use out of the regular @ 3 cups, and 9 to 10 weeks of use using the HC @ 1 1/2 cups. My system was very stable/mature, and my load, feeding habits, etc., very consistant, so I think these numbers are very reasonable. And although I could tell when it was getting close to the time to replace the media by the conditions in the tank, I would also confirm with a Hanna meter(a worthwhile investment).

 

[dkeller_nc]

I had a frogspawn, but it disappeared overnight. I heard they don't like phosphate. I'm thinking it was either phosphate or someone went on a murderous rampage. I'd only had it for a couple days, but it seemed to be doing okay. No tissue receding or secretions, all polyps out. Then one morning I woke up and it was a skeleton.

That's suspicious. Phosphates wouldn't have killed off your frogspawn, especially overnight. I'd encourage looking into your tank with a red flashlight a couple of hours after lights-out. You may have a gorilla crab or a flatworm in there. Or in the worst case, a bobbit worm.

 

[ucdcrew]

I bought the HC in case my tank needs more than the regular reactor can hold . I doubt it will though. This is probably a dumb question - but if BRS says my tank should take 3/4 cup of HC media. If the reactor holds 3 cups would putting 3 cups in there take out more phosphate? It seems like cheating which has not got me ANYTHING good in this hobby.

How big are gorilla crabs? They sound terrible.

 

[dkeller_nc]

In general, GFO will chemically combine with inorganic phosphate in the water to the extent that zero is left. That's assuming that there's enough GFO in the system not to become saturated. So in a sense, adding 3 cups will take out more phosphate than 3/4 of a cup if there's enough phosphate in the tank water that 3/4 of a cup will quickly become saturated.

Gorilla crabs can be very small (smaller than a dime) to much, much bigger. And they like coral, and not in a good way.

 

[downbeach]

I would start with less than is recommended, maybe by half, and go to the recommended amount as/if needed while monitoring the results step by step. Keep in mind that the GFO media needs to be kept fluidized to keep it from forming into a solid, so you'll need the space in the reactor. In your case I wouldn't fill it more than half way...you can alway replace it more frequently if necessary.