Gfo causing alk swings.

[CHEMCHEF]

Maybe I am using too much. Flow is good at a slow tumble.
I am using 5 tbs. my twv is 44 gallons.
I am finding my alk dips from 9 to 7.5 the first couple of days after I change out gfo.
Anyone else have this issue. Am I using too much?
Curious how others deal with this.

 

[MIKE NY]

IMO it absolutely does effect alk...I learned the hard way when it was first introduced..stupid me I followed the directions ...it also will strip the water too clean too fast which is another problem with corals..lower the amount your using..maybe only three then gradually increase it.

 

[greg 45]

I also learned this the hard way.
I used lanthiunchloride ,my thoughts arent the water becoming too clear its the alk swings that hurts the system.
Alk drops when using phosphate remover
I now always check alk before and after using any media

 

[CHEMCHEF]

I will be changing my gfo and carbon tonight. I'm going to use 2 tbs. and reduce the flow in reactor. Also going to use less carbon.
I'm trying to keep alk stable at 9.

 

[mbg75]

I had same issues when I ran Phosban brand.
No issues with ROWAphos or BRS. Then again it could have been I had too much flow through it.

 

[skene]

instead of basing what your usage is by tablespoons.. you should be using a scale to measure the amount that you are putting into your system. The proper usage of GFO in the system is to go by weight in grams per gallon. Then adjust by several to remove sand and rocks out of the equation.
Example... My total supposed volume is 90gal. so based on this I would use approx 70g of GFO.
But absolutely GFO like all phosphate reducing media will lower your kh.

 

[CHEMCHEF]

Weighing would equate to 7 tbs of gfo. I wind up with 2 more tbs than originally using.