Upgrading from 29 to 75 gallon process

I recently purchased a 75 gallon aquarium + stand for my father-in-law. He currently has a 29 gallon tank that's fully stocked, and honestly I'm not sure how often it's been maintained, cleaned, or had the filters rinsed out in old tank water, etc. It's one of those tanks that have been kind of left alone and the fish inside seem to have gotten used to the way it is. We got him this new 75 gallon to start fresh and also give some of his fish more space to swim as I do believe it's overstocked a bit, but I'm not sure exactly the best way to transfer over the fish.

Equipment list so far:

• 75 gallon aquarium
• Seachem Tidal 75
• The existing HOB (aqueon quietflow or tetra brand, not sure)
• Fluval E300 heater

The new 75 gallon will likely have to go where the 29 gallon is, so that complicates it a little bit, having to move the existing 29 gallon and possibly take it apart. Are there any suggestions for this kind of move? We will likely be starting with fresh new substrate (Fluval Stratum or maybe Seachem Flourite) and decorations, and it will not be planted. We'll likely run the old HOB in parallel with the Seachem Tidal in order to maintain the beneficial bacteria, but is that enough to cycle the new tank? Or will we need something like Tetra SafeStart Plus, Seachem Stability, etc? Also, if we do have to take apart the 29 gallon tank and move it out of the way, how long will the beneficial bacteria survive in that HOB?

Thanks in advance for the loaded questions, I'm sure I'll have more shortly. I'm just trying to figure out the best way to transfer fish with the least amount of stress and hopefully no fish loss.

 

Here's two suggestions:

1. Can you find a place where you can temporarily set up the 29? This will help a lot, even if for only a few days or weeks. Put the fish in bucket(s). Drain tank down low, move it to the temp position and re-fill / add the fish. This gives you more time to get the new tank up and running.

2. Carefully check all the existing water parameters. If nitrates are high and PH is low due to lack of water changes you'll have a lot of work to do acclimating the fish to new water.

 

What's your suggestion for acclimating for #2? Assuming nitrates are high/ph is low, what would be the best way to reduce fish stress during the move?

 

What's your suggestion for acclimating for #2? Assuming nitrates are high/ph is low, what would be the best way to reduce fish stress during the move?

First check and compare to your tap water. If there's a large difference between them the best way to correct it is to start doing partial water changes on the 29 every few days until it's close to the same. Then you can safely move a few fish at a time to the new tank as you build the cycle on it. This is why #1 is so beneficial.

 

. . . We'll likely run the old HOB in parallel with the Seachem Tidal in order to maintain the beneficial bacteria, but is that enough to cycle the new tank? Or will we need something like Tetra SafeStart Plus, Seachem Stability, etc? Also, if we do have to take apart the 29 gallon tank and move it out of the way, how long will the beneficial bacteria survive in that HOB?

I don't think anyone answered that question. If you move the old filter to the new tank, and the media stays wet, the tank should immediately be able to handle the same bioload as the old one. Adding any commercial products isn't necessary.

 

First check and compare to your tap water. If there's a large difference between them the best way to correct it is to start doing partial water changes on the 29 every few days until it's close to the same. Then you can safely move a few fish at a time to the new tank as you build the cycle on it. This is why #1 is so beneficial.

Just curious, what's the worst that can happen if the fish are transferred to the new tank immediately and the HOB filter is moved as well. I understand the parameters would be a little different, but the new tank water ideally would be much cleaner with less waste and toxicity, would that still stress the fish out a lot and cause fish loss? I'm asking because if I don't transfer the filter over, then it won't be cycled and we'll have to do a fish-in cycle.

 

Just curious, what's the worst that can happen if the fish are transferred to the new tank immediately and the HOB filter is moved as well. I understand the parameters would be a little different, but the new tank water ideally would be much cleaner with less waste and toxicity, would that still stress the fish out a lot and cause fish loss? I'm asking because if I don't transfer the filter over, then it won't be cycled and we'll have to do a fish-in cycle.

As far as I know the only reason not to do it that way would be if the existing tank has been sitting for a long time with no water changes. It's possible the water parameters would be far enough off from the tap water to cause problems.

 

As far as I know the only reason not to do it that way would be if the existing tank has been sitting for a long time with no water changes. It's possible the water parameters would be far enough off from the tap water to cause problems.

Thank you, yeah I think it's been sitting for a while the way it is, with the occasional top off and some water changes with some pitchers, but probably not much more than a couple gallons. I'm sure a new tank with fresh water would be much cleaner but I guess it can stress the fish out too much?

 

So to confirm, you are thinking of moving the HOB only but not the hardscape? Remember that much beneficial bacteria is on the hardscape as well per my understanding.

 

Thank you, yeah I think it's been sitting for a while the way it is, with the occasional top off and some water changes with some pitchers, but probably not much more than a couple gallons. I'm sure a new tank with fresh water would be much cleaner but I guess it can stress the fish out too much?

Yes, it could stress them. Without knowing the parameters of the water in the old tank compared to the fresh water it's impossible to give better information.

 

So to confirm, you are thinking of moving the HOB only but not the hardscape? Remember that much beneficial bacteria is on the hardscape as well per my understanding.

Possibly a couple of the decorations he has, but besides that yeah. Switching from these rocks he has to gravel/sand.

 

Possibly a couple of the decorations he has, but besides that yeah. Switching from these rocks he has to gravel/sand.

So the current substrate is rocks? If it were me, I would consider placing at least some of them in the back of the 75 on top of the new substrate for the first month to help transfer/establish more of the beneficial bacteria colony. Then remove them afterwards. Just a thought.

 

So the current substrate is rocks? If it were me, I would consider placing at least some of them in the back of the 75 on top of the new substrate for the first month to help transfer/establish more of the beneficial bacteria colony. Then remove them afterwards. Just a thought.

Yeah, more like large pebbles actually with a ton of gunk in between and under. Part of the reason why we decided to upgrade tanks and start fresh.