# Sand and canister filters



## TKC747 (Dec 5, 2008)

I guess its a no brainer that you shouldn't let sand get into the uptake of a cansiter filter. What is the worst thing that can happen if sand should get into a canister filter? How do you clean it out? What should you do?

Also, when adding substrate to a tank which has been cycled,

1. turn off the filter
2. let it settle before turning the filter on

how long should I wait until I can turn on the filter again?

Is it better to add substrate before cycling?


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## cjacob316 (Dec 4, 2008)

yes it's better to add substrate before the cycle, the substrate creates a good surface for bacteria to grow. plus it's easier to do it in an empty tank

witha canister you go through all the media before the impeller so you should be fine


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## Rhinox (Sep 10, 2009)

> witha canister you go through all the media before the impeller so you should be fine


+1 :thumb:

Sand should damage a canister filter, but it is still an inconvenience because it can clog the filter.

I agree with cjacobs thoughts on adding substrate first. However, I wouldn't call it absolutely necessary to add substrate. Your filter should provide more than enough surface area for bacteria to grow, and it shouldn't effect the cycling process if the sand is removed. Afterall, many fish store tanks do not have substrate at all, and they don't seem to have cycle problems.

That being said, if I was going to be adding sand, I would do it first before adding water.


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## Toby_H (Apr 15, 2005)

As mentioned, with typical canister filters the water moved through the media before contact with the impeller. Thus sand does not damage impellers of canisters. With HOB filters the water comes in contact with the impeller before the media, so sand is harmful to HOB filters...

I still consider it a good idea to turn off filters when adding / stirring sand to keep it from unnecessarily clogging a canister filter. The filter should be turned off long enough for the sand particles to settle, which should only be a matter of minutes. I suggest turning the filter on before the resulting cloudiness settles. This would promote removing the 'dust' as opposed to letting it settle.

It makes sense to me to add sand and any other decor prior to cycling. This will promote bacteria growth on these items. If sand is added after cycling, the sand will 'smother' any bacteria established on the bottom glass. Although this would only remove a small % of the overall bacteria which would quickly be replaced.


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## cjacob316 (Dec 4, 2008)

yeah i keep sponge prefilters on my hob's


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