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32 Posts
Discussion Starter · #1 ·
I am in the process of combining two tanks into one while reusing some setup and equipment. I am wondering what to expect in terms of cycling the new tank and how to be sure cycle is done. I expect quick cycling process but I am afraid in particular that I may misjudge if nitrite spike has passed as it may look very different under these conditions.
I already took down 75gal and saved substrate but it is sitting relatively dried out for about a month. 50gal will be dismantled the same day as new 125gal will be set. 50gal substrate will go directly from it to a new one, will be combined with saved 75gal substrate. 75gal used two Rena Filstar xp3 canister filters. 50gal uses one Eheim 2213 and one Eheim 2215. Rena canisters have been inactive and cleaned for about a month. Eheim will be active up to the transfer. I like Eheim media so I will combine these filters as follows: I will use two standard Eheim media types, mechanical and biological (small cylinders and small spheres) each in one of drawers of Rena filters. This media I expect to still be live. There will be one rough sponge from Rena original setup (dried and presumed dead) and I will replace final media in Rena with 2" 40ppi Poret foam. This will be brand new, never used. I have good experience using this type of Poret as the final step in my Eheim filters for a long time but the size and shape prevents me using old live Poret from Eheims... I will use just two Rena filters on 125gal but as explained with most of the media in them from active Eheims. Most of decorative rock will come from old 75gal, they've been dry for a month. One about12"*15" fake rock will be used from active 50gal. I will house fish (Malawi Mbuna and Haps) in other existing aquariums but at crowded conditions so faster I can have new 125gal ready-better.
So, any ideas what can I expect in terms of cycling under these conditions? Any advice?

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Any dry or cleaned media, rock and substrate will probably have minimal dormant bacteria after a month so I wouldn't rely on them to help cycle the new 125G tank.

Using any media from the current active Eheim should work as well as the substrate from the 50G you will be reusing.

While inconvenient, why not just use the 2 mature Eheims on the 125G while also using the 2 cleaned Filstar filters and let them get established for a few weeks? Using this method should allow you to stock immediately within reason of course depending on the number and size of the fish.

My best guess is that using your original plan should be fine, especially if you can add a couple fish at the set up time, but monitor for any ammonia or nitrite spikes and act accordingly.

32 Posts
Discussion Starter · #3 ·
Thanks for the suggestions, I followed them up "half way" and everything went well. Here is my experience with this process
so others may use it as a guidance what to expect in a similar situation:
In addition to the initially intended process, as suggested by @Deeda I kept one of mature Eheims 2215 along.
After initial day, empty aquarium with water treated with Prime, API pH8.2 and baking soda to get Ph8 and KH 13
on second day I did "semi-fishless" initiation of the cycle. Before adding clear ammonia it and nitrites were 0. I added it to raise ammonia to
0.5. Testing on third day showed ammonia back to 0 and nitrites still 0. I added 4 fishes, 3 Yellow labs about 3-4" each
and 5" common pleco. From this point on I treated water with 2 cap-fulls of Prime to safely alter any ammonia or nitrites
every 24hrs (two cap-fulls should treat 100 gal and by Seachme instructions bond will last 24-48hrs, erring on safe side).
On fourth day nitrites registered slightly up, estimating at 0.1 (test colors jump 0 to 0.25),
ammonia still 0. On fifth day ammonia jumped to 1, nitrites dropped to 0. Sixth day ammonia went further up to 2,
nitrites still 0. Seventh day ammonia reached the peak in the morning (I measured 2-3 times per day) of 4,
trace of nitrite, estimating 0.1 appeared. By evening of seventh day ammonia dropped to 1, nitrites rose
to their maximum in this cycle of just 0.25. I added remaining fishes, 20 Mbuna/Haps in total and 3 catfishes in total.
Eighth day ammonia dropped to 0, morning nitrites were still 0.25 but by evening they too dropped to 0.
At this point I am assuming cycle done, this morning both are 0 and other parameters are good pH8.2 and KH 16.
Prime indeed protected the fish, they have not shown any symptoms of harm, all fine and well.
As I was worried, nitrite cycle was harder to detect lacking great "boom" as in cycling completely
new tank but it was detectable (and it is better that it was so mild).
Side note-Prime binding of ammonia and nitrites does not affect measurement with typical kits,
nor does it change concentrations. It just makes those not harmful to fishes for a while.
I think that using one old filter completely and doing a "fishy" cycle did help process along. Thanks for the ideas.
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