I am wanting to seed my new large tank from the smaller tank my fish are currently in before I move the fish. However my fish are currently being trated for an outbreak of white spot in the smaller tank. Im worried if I move media across that I will infect the new aquarium and reinfect my fish once they move?? Any advice. I have already moved some plants out of the old tank in to the new.
Any advice would be great.

Hi

A quick run own on the Ichthyophthirius parasite's life-cycle should show us what to do.

Usually we notice an outbreak of Ich when the white spots appear on fish. That is known as the trophont stage in the life-cycle, when the parasite is actively feeding on the fish and maturing. Once mature, it bursts out from under the fish's skin, attaches itself to a plant or other surface and forms a capsule around itself. This is the tomont stage. While encapsulated the parasite divides multiple times, producing hundreds of copies of itself which eventually hatch from the capsule. These newly hatched parasites are called theronts and they swim off to find a host and repeat the cycle.

The white spot parasite can only be killed by meds during the theront (free swimming) stage of its life-cycle. At all other times (when embedded under the host's skin, or when encapsulated), it is immune to meds. The entire life-cycle takes about a week at typical tropical temperatures (25C); at lower temps the cycle takes longer.

On that basis it's usually best to continue to medicate until a couple of days after the last white spot has disappeared to be sure of killing all encysted parasites when they hatch into theronts. That should take care of the infection in the tank and if no new spots are present, there will be no whitespot in the tank.

It is possible that some encapsulated parasites (tomonts) have been moved to the new tank with the plants, but as long as no fish are moved over for at least a week, any that hatch into theronts will die due to the lack of a host as they only have a very short time in which to latch on to a fish - no fish, and they will die of starvation very rapidly.

Thank you for the advice. As always greatly appreciated. So on that will I be ok to squeeze the sponges out and transfer more plants then if im not planning on moving the fish for at leat 2 weeks??

The safest way to do this is to move the plants and wait a week or more then move the fish and move the media from the filter into the new tank's filter at the same time. That will prevent or at least minimise any potential ammonia/nitrite spikes. There's not really any point squeezing the sponges into the new filter as unless you intend doing a full fishless cycle, the very small amount of bacteria that would be introduced would not survive without a food source (i.e. ammonia).

Thanks, I will do that. I will be testing the water every day once the fish are moved to keep an eye on levels. Its all very stressful moving fish around just cant wait till they are in their new home and happy. I am in the process of trying to grow algae on pebbles in my conservatory for my Plec to eat as was worried he wont have enough to eat in new tank. Bought some algae wafers just in case. Thanks again.

Hope it all goes well