Going from 46g to 75g tank help

[firefightered]

I'm up grading from my 46 gal. reef tank to a 75 gal. The question i have is can I use my old sand and just add more (which one Live or aggragate). I do not want to kill what I have by going through a cycle. My 46 has been set up for about 5 years. Any suggestions?

 

[1fishmonger]

Using the old sand and stirring up during the transfer will likely cause a nitrate/ammonia spike. I'd recommend new sand and then seed it with sand from your old tank. I suppose you could use the old sand if you siphoned it out and then let it sit in the new tank for a while to be sure there's no spike. Either way..Hopefully you can have the 75 set up before breaking down the 46.

 

[ritter6788]

Ditch the old sand. Either add new sand or go bare bottom. Old sand is full of nasty stuff.

 

[skinz78]

Get rid of the old, you'll be better off in the long run anyhow.

 

[firefightered]

So if I put all new sand in, I'll have to let it cycle all over again. The problem would be I want the 75 in the same spot as the 46. This could be tricky...... Any suggestions?

 

[jt_milstead]

Ive used the same sand in upgrades. You do have a risk of ammonia spike. What usually do is vacuum the sand to get out most of what has settled into the sand. It takes some time. I have also added the old sand on top of new sand, or on top of new "live sand".

 

[SeahorseKeeper]

I would use new sand and maybe a cup or two of the old. This will give the new sand some of the biodiversity from the old sand. I would recommend having plenty of saltwater and good test kits when you make the transfer. This way you can be prepared for any parameter swings that may happen when you do the transfer.

 

[cdangel0]

Really the deciding factor in deciding whether or not to use the old sand whould be - condition of the sand bed. Consider the depth as well as the amount of critters living in it. All too often in this hobby we see tanks that have been set up for 7,8,10 years suddenly crash due tot he sand bed. When you have even a relatively deep sand bed ( >1.5") you'll have pocets on anerobic bacteria which are great for nutrient reduction and nitrate consumption, but the moment they're exposed to oxygen, they die, when you have a large population of bacteria die instantly it creates a significant ammonia spike that the aerobic bacteria can't consume before it poisons the wntire tank. Now if you have a large population of sand sifting cleaners this may not be an issue as they will generally prevent dead anaerobic spots from exiting, but there's always a risk there's a dead spot you (and the snails) don't know about.

I would follow the above advice (personally anyway) and use fresh sand for the new tank, take a few cups of the old and seed the new sand. Reusing the existing live rock and some of the sand will minimize any cycle you may experience, I've set up a new tank using 100 lbs of live rock from an existing tank and saw no noticable cycle at all.