Seeding filters in new tank: Did I screw up?


Lifetime Charter Member
Lifetime Member
Mar 3, 2007

Last Saturday (8 days ago) I did the main and heavy planting of my new 90gal. I tried to follow suggestions of Tom and others, for how to minimize new-tank issues.

I added zeolite to filters, seeded new filters with biomedia and mulm from established filters, and even seeded the new substrate with mulm. I think I recall reading a post by Hoppy who suggested using a turkey baster to squirt mulm into bottom of new substrate! Which I did.

I think I screwed up. Since the initial planting (8 days ago) there have been no inhabitants in the tank. I naively assumed if the plants were being fed, so was the biofilter. But I now realize that the seeded biofilter may be 'dead' because there was no ammonia to feed it.

25 Amano shrimp were added 2 days ago. Today I added one SAE and 5 tetras (Day 9 of tank). Some time next week 4 additional SAEs and 20 more Amano shrimp will be added.

Is it pretty certain that my efforts to avoid a full "cycle" are toast?

Should I do the seed again? I can still take filter gunk from established filters and put in new filters (again). My method last time was to clean filter pads from the established filters in a bucket of tank water, then extract the mulm/gunk from the bucket for the new filter.

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Lifetime Charter Member
Lifetime Member
Jun 21, 2009
Surprise, AZ
Probably Not

Hi growitnow,

Yes, whatever you have, in a heavily planted tank you should catch a bit of a break. The little critters are probably better off than you think.

When in doubt add mulm, filter stuff, goo out of an established substrate, sponges whatever.



Guru Class Expert
Oct 26, 2007
Brisbane, Australia
The 'good' bacteria colonies in the filter will grow/shrink in response to how much 'food' is available for them. So if you take a filter from a matured tank with a heavy load of fish and put it into a tank containing zero fish, the bacteria colony will shrink. I suppose die off completely if placed in a completely bare sterile tank. At least that is my understanding. Makes sense I suppose.

As Biollante says, I think the plants should help out with the ammonia/nitrite. In my experience ammonia/nitrite test kits are generally pretty good - I used them a lot when I use to breed fish and was regularly setting up new tanks, so you could probably use one to keep tabs on these nasty chemicals in the early days.

Probably a bit hard to tell with SAE's and shrimps, but I usually found my breeding stock would go off there food as soon as the ammonia/nitrite became detectable on the test kits.