GFO problems

[klwheat]

Ok, so I'm wondering if anyone else has had this problem. I was having a bit of gha growth, and my phos was up to 0.08. Decided to put some gfo in a small reactor and bring it down. Over the course of a month my phos has dropped to 0.02...great! However, I noticed that my elegance coral wasn't happy. I also noted a "cloudiness" to my tank. Last week, my alk was 6.7 (normally right around 8) and this week my alk was 5.6! The only supplements I use are kalk in my ato. Ca has been stable at 440-450 and mag at 1280.
After doing quite a bit of research, it seems that sometimes gfo can cause calcium carbonate precip and drop alk. I'm bringing my alk up over a few days with brs sofa ash and pulled the gfo reactor. Alk is now close to 7 and my elegance seems happier. I'm replacing my skimmer (which is currently undersized) and will be watching my parameters closely. Wondering if anyone has similar experiences with gfo causing major alk drops?!

[alton]

I ran into this once using Rhowaphos, I was trying to get a handle on bubble algae so I thought I would strip the phosphates and ended up losing a ton of coraline algae.

[FarmerTy]

I've honestly never encountered myself but I've heard it can happen. How much GFO were you running? Substantial?

[Justin]

I've seen this several times in my tank. I used to rely heavily on GFO for PO4 control as I feed pretty heavily in my tank. I would always notice extremely sharp declines in my Alk numbers when replenishing my GFO every month. As you did, I did some research and found that not only was the GFO precipitating out some of my parameters, it was also stripping my tank way too much. I've lost several nice colonies to being naive and adding too much GFO to try and counteract my algae issues. I know that corals like to have some nutrients in the tank water to be able to grow and thrive. Now I only use about a cup of GFO for a 155 system and I use chaeto and a fuge as my primary defense against high nutrients. My PO4 reading is a bit high at .13 but my corals have some great PE and they are growing well again. My alk has been steady at rough 172 ppm, a bit high but I will let my numbers slowly go down over time before adjusting my Ca reactor to make them level again.
I would personally like my PO4 numbers to be lower but I'm just waiting on my macro algae to kick in and absorb the excess nutrients.

[FarmerTy]

I've seen this several times in my tank. I used to rely heavily on GFO for PO4 control as I feed pretty heavily in my tank. I would always notice extremely sharp declines in my Alk numbers when replenishing my GFO every month. As you did, I did some research and found that not only was the GFO precipitating out some of my parameters, it was also stripping my tank way too much. I've lost several nice colonies to being naive and adding too much GFO to try and counteract my algae issues. I know that corals like to have some nutrients in the tank water to be able to grow and thrive. Now I only use about a cup of GFO for a 155 system and I use chaeto and a fuge as my primary defense against high nutrients. My PO4 reading is a bit high at .13 but my corals have some great PE and they are growing well again. My alk has been steady at rough 172 ppm, a bit high but I will let my numbers slowly go down over time before adjusting my Ca reactor to make them level again.
I would personally like my PO4 numbers to be lower but I'm just waiting on my macro algae to kick in and absorb the excess nutrients.
That's interesting. I use GFO on a monthly basis and have never noticed a dip in my alk when I swap in the new media every month. I'm pretty anal about my alk testing too, almost daily.

What GFO are you guys using? How much? I use about 1-1.5 cups on a total 250 gallon water volume and my phosphate levels stay at 0.03 ppm. I do have some light algal growth but that's intentional so my tangs and angels have stuff to pick at.

[Justin]

I primarily use BRS basic GFO. How often do you feed your fish? Due to my anthias harem, I feed my tank about 4-5 times a day. I feed small cubes of mysis 3x and my apex auto feeder goes off twice a day as well. Its a lot but I try to keep my anthias nice and healthy. Everybody seems to love the feedings. Oh, I also put a small sheet of Nori in my grazer every other day for my Powder Blue and Foxface.

[FarmerTy]

I feed about 5-6x/day. About 3-5 cubes of frozen/day, pellets through autofeeder, and half sheet of nori.

Here's my stock:

https://youtu.be/ToUxVy2J54g

[FarmerTy]

Just a thought to the OP but perhaps the decreased phosphate level increased your coral growth rate in your tank. Without adjusting your dosing to match the faster growth, your alk will drop and then all the corals will suffer from low alk.

I've seen that scenario much more than I've seen GFO physically lower alk levels directly.

[Troy Valentine]

http://reefkeeping.com/issues/2006-09/rhf/

This is a good article about the correlation between Calcium and PO4, and how high PO4 levels will inhibit calcification.

[klwheat]

Thanks for the ideas and article. I thought about the idea of decreased phos increasing calcification...but my calcium never budged!
My alk dropped significantly...but my calcium stayed at 440. Also had noticed (actually my oldest daughter noticed) that my tank seemed "not as clear" as normal. I read a good article about GFO causing alk precipitation..trying to find it to share.

[klwheat]

ahh...here is the article.
http://www.reefkeeping.com/issues/2004-11/rhf/