Media from brackish tank?

[Biochembob]

I have an established brackish tank and I'm running a heavily modified filter that has lava rock as a biological filtration. This setup works extremely well and I was wondering if I could use some of that lava rock in my AIO filter to kick start the cycle. I also have access to pure aqua ammonia to do something like a 1 ppm dose. Does this sound reasonable?

 

[blaxsun]

Honestly, no idea. Hopefully someone else can chime in.

 

[MaxTremors]

I would not use lava rock. First, it can leach metals into the water, which is not conducive to inverts surviving. Second, it is not very porous, the pores are large and not connected, so it doesn’t have a lot of surface area (compared to aragonite coral skeletons or live rock), so it won’t be very effective for biological filtration and definitely won’t be capable of denitrification. Third, it won’t help buffer PH, Alk, and Cal. And lastly, it just doesn’t look right, it doesn’t look like a reef.

Given the risks and the unsuitability, I would definitely recommend not using it. I would pick up either some real live rock (best), some dry rock that you seed with a little bit of live rock (better), or use dry aragonite rock (good).

 

[Biochembob]

I would not use lava rock. First, it can leach metals into the water, which is not conducive to inverts surviving. Second, it is not very porous, the pores are large and not connected, so it doesn’t have a lot of surface area (compared to aragonite coral skeletons or live rock), so it won’t be very effective for biological filtration and definitely won’t be capable of denitrification. Third, it won’t help buffer PH, Alk, and Cal. And lastly, it just doesn’t look right, it doesn’t look like a reef.

Given the risks and the unsuitability, I would definitely recommend not using it. I would pick up either some real live rock (best), some dry rock that you seed with a little bit of live rock (better), or use dry aragonite rock (good).

I only planned on using a small amount to kick start the new media.

I would not use lava rock. First, it can leach metals into the water, which is not conducive to inverts surviving. Second, it is not very porous, the pores are large and not connected, so it doesn’t have a lot of surface area (compared to aragonite coral skeletons or live rock), so it won’t be very effective for biological filtration and definitely won’t be capable of denitrification. Third, it won’t help buffer PH, Alk, and Cal. And lastly, it just doesn’t look right, it doesn’t look like a reef.

Given the risks and the unsuitability, I would definitely recommend not using it. I would pick up either some real live rock (best), some dry rock that you seed with a little bit of live rock (better), or use dry aragonite rock (good).

My plan was to throw a half dozen in the back of my AIO for a few weeks and then take them out once the tank is cycled.

 

[damsels are not mean]

Depends on how brackish. IIRC the switch from fresh to saltwater nitrifiers happens around 6-11 ppt. So the saltwater nitrifiers start to grow at 6ish and the freshwater ones start to die at 11ish. Dr Tim recommends 10 ppt as the dividing line. I won't repeat what's above but since you are not keeping the rocks in long I can't imagine it's a big deal.