tank switch

[docjones]

I currently have a 55g tank that I am getting ready to tear down to put up my new 125g tank. My question is with new water (RO/DI saltwater I have made) and new Live sand (was told not to use the old sand) will the tank go threw a cycle? I do have 120lbs of Live rock that has been in the 55g for 6+ months that I will be putting in the 125g. But I just dont want the tank to cycle since I do have live stock that needs to transfer as well (Niger, Lion, and clown). So is there any advice that could help make this a success?

[Shooter7]

If you have that much live rock to move over, and you're moving the same livestock into the bigger tank, I do not foresee you having a true "cycle" in the new tank. I moved the rock from my 26g, some established live rock I picked up from a local guy, and some dry base rock to my 120g when I first set it up and had no cycle at all. I did, however, have some of the usual "new tank syndrome" symptoms of some algae forming on the sand and glass for awhile, along with a little cyano. Kept parameters good and ample flow and it all went away over a short time.

[cardiffgiant]

Last Spring I emptied my 55 (saving all of the water), put my fish and LR into buckets, got rid of my crushed coral, and added a new sand bed. Even using the same LR and water, I did have new tank symptoms for 3-4 weeks.

I measured my parameters almost daily, and stepped up some water changes, but I got through it without losing specimens or having my tank look terrible.

[osprey77]

you will have a spike, have prime or stabalize ready and be prepped to do some serious quick water changes. Until your sand is seeded there won't be a cycle but you will spike your nasties.

[Shooter7]

For what logical reason would he have a spike? He will be putting the same amount of livestock into a tank with the same amount of established rock he's got now. That amount of established rock will handle the move just fine, as it's already doing in his current tank. I didn't have so much as a tiny indication of a spike in my move and I tested three times a day for the first week.

[cardiffgiant]

Originally posted by Shooter7
For what logical reason would he have a spike? He will be putting the same amount of livestock into a tank with the same amount of established rock he's got now. That amount of established rock will handle the move just fine, as it's already doing in his current tank. I didn't have so much as a tiny indication of a spike in my move and I tested three times a day for the first week.

Logically, there should be some kind of a cycle for a new sand bed. Maybe your higher volume of water prevented any change in your parameters.

[Shooter7]

Can you explain why there would be a "cycle" for a new sand bed? The rock would handle the biofiltration just as it had been doing. The sandbed will be populated with bacteria over time, but there is no reason for a cycle to occur. A cycle occurs when there is more waste in the water than the bacteria can handle. If the bacteria in the rocks is handling the waste fine, as it should do because it's already doing that in the current tank, then there will be no imbalance and, therefore, no cycle.

This is, of course, assuming no increase in the current bioload...

[docjones]

There will be no increase in bio load, in fact I plan to give the tank a month or so before adding any new live stock.

[cardiffgiant]

Originally posted by Shooter7
Can you explain why there would be a "cycle" for a new sand bed? The rock would handle the biofiltration just as it had been doing. The sandbed will be populated with bacteria over time, but there is no reason for a cycle to occur. A cycle occurs when there is more waste in the water than the bacteria can handle. If the bacteria in the rocks is handling the waste fine, as it should do because it's already doing that in the current tank, then there will be no imbalance and, therefore, no cycle.

This is, of course, assuming no increase in the current bioload...

Assuming that the rock will handle 100% of the bio-load, you are correct. As long as any nutrient that breaks down on the sandbed is handled by the rock (and other filtration) then, in theory, there would be no increase. However, nitrifying bacteria grow based upon available food. So, in theory, wouldn't the sand bed stay baron if the LR were handling the full bio-load?

[Shooter7]

As I understand it, the bacteria of the sandbed are a bit more involved with using up nitrates and converting that. Once you start getting down into the levels of aerobic and anaerobic life in the sandbed, I started getting a glaze on my eyes, so I'm not going to profess to knowing thoroughly the full functionality of the sandbed with regards to chemical breakdown, however, the parts of chemistry that you're worried about in a "cycle" are the ability to break down ammonia to nitrite and nitrite to nitrate, which live rock will do a fine job of doing...and if it does a fine job of doing that, then there will be no "cycle" in the sense that we talk about a cycle. Now, there may be less of an ability at the start to handle the breakdown of nitrates, but an increase in nitrates is not as critical to the fish as an acute increase in ammonia.

If the tank had been bare bottom, he'd be relying on that rock and skimmer to handle everything...and still wouldn't have a cycle.

[NYIntensity]

What's the point of changing the sandbed?

[docjones]

I have read that when you stir up the old sand you can release built up Nitrates back into the water causing more harm then good. So I figured the best route would be to buy new sand to keep that from happening.