Substrate Change On Cycled Tank

[zoogy]

I'm planning on doing a substrate change on a 29 gallon cycled tank today. I plan on re-using about 70-80% of the existing water and keeping the old filter media unchanged. Then I'll changed 100% of the substrate and clean out the interior of the tank really well before refilling it with the old water and putting my fish back in.

Any advice/suggestions? Will that stress out my fish too much? Do ya'll think that will have a detrimental effect on my bio filter?

 

[minnnt]

I would probably opt for stirring the substrate up, getting some of the 'filth' mixed into the water, save about 10% of the water to put back into the tank when set up with the new substrate. Old tank water doesn't really do anything for the bacteria. Keep your filter wet in the old tank water. Ensure the new water is well dechlorinated also and of similar chemistry and temperature.

 

[luke4868]

I would probably opt for stirring the substrate up, getting some of the 'filth' mixed into the water, save about 10% of the water to put back into the tank when set up with the new substrate. Old tank water doesn't really do anything for the bacteria. Keep your filter wet in the old tank water. Ensure the new water is well dechlorinated also and of similar chemistry and temperature.

+1 to that

I changed my tank last week from Gravel to Sand, and just left filter media in with tank water in a bucket with the fish whilst I changed it over, they loved the new sand to play with, and all water parameters are fine too. You shouldn't have a problem at all.

 

[Tizer]

It wont hurt to have 100% new water, as long as its at a good temperature and you dechlorinate it.

 

[StandbySetting]

It wont hurt to have 100% new water, as long as its at a good temperature and you dechlorinate it.

And the parameters are the same.

 

[hanny93]

I wouldn't say the params will be a big issue, unless OP uses pH buffers or other water treatments.

They can always acclimatise anyhow.


I'd suggest taking a bucketful of water out, putting filter and heater in, and some plants if you have them, then transferring all the fish to the bucket (or multiple buckets if you have a lot).

Then use a gravel cleaner to stir up all the gravel, there will be a LOT of muck hidden away in that gravel, and just siphoning the water out that way. Then once youve got all the water out, just scoop all the gravel out.

Then put your (washed!) sand in, and slowly fill up the tank with a bowl on the sand so you dont stir it uo.

Then put your heater in the tank and the plants and any ornaments, then once the sand has settled down a bit, put the filter back in.

Then the fish if the params are the same and the temp. If not just wait until they are.

It's quite simple really, just need to do it right!

 

[StandbySetting]

Tap water is acidic, due to the CO2 the water companies dissolve into it, also the mineral content may vary, which can lead to osmotic shock as the fish will find it difficult to osmoregulate due to drastic changes in the concentration of Na[sup]+[/sup], K[sup]+[/sup] and Cl[sup]-[/sup] in the water. 2*50% water changes would be much better than a large near 100% one.

 

[zoogy]

Thanks for all the great advice. 10 hrs later and I'm finally done. I ended up using a 20 gallon tub and setting up my heater and filter in it like a little mini fish tank with the water I siphoned off. Worked great! The fish didn't act stressed at all & they love the new sand!

Thanks again... ya'll have the best advice on the web!