If you wish to keep the 10g tank up and running and cycled, you could add a 1/2 a raw prawn as an ammonia source. This would save you from manually adding ammonia every day. I am unable to buy high-grade ammonia here in Oz, so this is what I use for fishless cylcing. Just drop it in and it will decompose and disintegrate into nothing. When it is close to gone add another 1/2.
But if all you want is to keep some filter media ready so that you can set up your 10g in a moments notice, you probablt have other options. Depending on the filters you have, you might be able to put some of the sponges/media belonging to the 10g in the filter belonging to the 29g. Then, if you need to set up the QT, you can just go get the seeded media from the filter. Alternatively you could run the foilter for the 10g on the 29g tank. You have two filters, bit again, you can easily move the 10g filter if needed.
Sharon : Melbourne, Australia
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4x4x2 FW planted | 15g FW planted | 3.5g FW planted pico