Cloudy tank - help please

[NotSoEnthusiast]

Hi all

I've had this reef tank a couple of months and in the last 2 weeks its gone very cloudy. The fish seem to be coping fine but I can barely see them most of the time. I've done a few small water changes but not to much effect. I've tried uploading photos of it but can't because of the file size limit. Any suggestions on how to address this please? I've read about possibly keeping the tank dark for a few days or treating it with carbon. Any opinions on these options? I've not got any corals but just have a few snails and crabs.

Thanks

[CheezotheClown]

The tank is "cycling". Advise is generalised because you haven't provided much by way of details. Tank size, ie volume? Sump? Liverock - how much, how live when it went in, when? What are you running for denitrification - chemical, deep sand bed (DSB) etc. What livestock - how many fish, which ones, how big?

At a guess I think you've got the tank, filled it with salt water and added "a few snails and crabs" along with a few fish and now the required bacteria is starting to crank.

So the horse has bolted. The tank should have been cycled which can take weeks before adding fins. The only option I see you have at the moment is to perform large (60-70% minimum) water changes daily. You will need to test for nitrite and nitrate to observe the cycle. In the meantime plenty to read - start here and follow the rabbit hole.

You will also note that this forum also automatically parses select words which link to pages in the Reefpedia so you don't even need to search to get started.

[NotSoEnthusiast]

Ok thanks. Tank had nothing but rock (already cured) for 4 or 5 weeks, then added some inverts then a few weeks later added a clown and blue tang - both medium sized. Total tank size is 270L with a sump. Got matrix rocks in the sump for denitrification. Also have a protein skimmer.

Does that change anything you'd recommended?

[CheezotheClown]

Yeah, doesn't seem quite as critical as first assumed. Keep in mind without testing and tracking any changes in parameters it is still somewhat working with assumptions. The cloudiness does still seem to be bacterial blooms associated with everything finding it's groove. Probably aim for 50% water changes. How much are you feeding? Is the skimmer pulling skimmate - is it dark or light coloured and how long to fill the cup? Until the system settles anything like livestock additions and/or food can throw the equilibrium and result in mini (or major) cycles. With that in mind, probably hold off feeding anything. How long since the fish were added?

How much matrix and how much liverock (both denitrify) btw?

I just re-read my reply so apologies if it sounded a bit terse. It wasn't intended.

[NotSoEnthusiast]

Ok thanks.
Feeding once per day - just a pinch of floating pellets. The fish have been there 2-3 weeks now. Skimmer is filling about every 1-2 days with a darkish mix. Darker than the tank water but not black. I'm actually not confident with the skimmer as I haven't really used them before.
The live rock is stacked about 3/4 of the depth of the tank in a bit of a pyramid shape. Its a 70cm cube tank. Matrix is through most of the base of the sump plus a big chunk in the intake part. But hard to quantify that without a picture sorry.
How long could the fish go without feeding?

[NotSoEnthusiast]

Another update. I've made 5 or 6 water changes of about 30%. I can't do more than that because I don't have the storagr to mix up more than that. Its a little better but still quite cloudy. Fish and inverts are all fine with the exception of a couple of trochus.
Any other suggestions? Should I continue with the water changes? Or will the bacteria sort itself out from here?
I aim to change the filter wool every other day as that seems to be getting filthy quickly.

[Basenji]

Whilst not ideal for long term use on marine tanks, a canister filter filled with filter wool and/or carbon can prove useful for short term tidying up of water quality issues.
The canister can also be used like a vacuum cleaner to pick up detritus from the rocks and substrate, and return the water back to the tank. Certainly allows you to clean things up without high volume water changes.
The more detritus you can pull out, the less will there to break down and feed further bacteria.

Just be sure to clean the filter out regularly so the collected organic material doesn't break down and recycle the problem.
By regularly, I mean at least once a day if running continuously, or immediately if you've been doing a manual vacuuming session.

I really recommend reading the following link in detail - more than once. It is a good description of the cycling process that has helped many to better understand the complexity and dynamics of setting up a tank.
http://www.masa.asn.au/masawiki/index.p ... _to_Expect

Also, the RTAW Wikipedia entry on Cycling