Question: Filters, parameters, and other general annoyances!

[Minniechild]

Hey all!
So just did a 40L water change (forty out, forty seven in on a 180L tank ) after having it settled for a few weeks (It's been guppies and cherry shrimp), and have found my Nitrite parameters after the change have gone whacko. GAH!
I have sand, coral sand and then river stones (All bigger than all my axies' heads (From the 12cm one up to my 20cm one- And no, they're not in the same tank). Parameters are:
straight after change: pH 7.8, NH3/NH4 >0.25ppm, NO2 0ppm, NO3 40ppm (See pic 1).
four hours later: pH 7.8, NH3/4 0.25ppm, NO2 0.50ppm, NO3 approx 30ppm. Further, I added in some aquarium salt (two tablespoons- I'm on tank water for the various aquaria).
So should I be monitoring that for the time being to allow the bacteria time to tackle it? Or another (slightly smaller) water change tomorrow?

Also, in terms of filtration, I'm currently using a pump powered box, rather than the aquaone F3 internal power filter because of the cherry shrimp (I rather like them, and would be rather disappointed if I lost them all, and I was cautioned against using it lest they were all sucked up and into oblivion...), so I'm wondering if there's a way to adapt it so that it would be shrimp-safe? (And yes, I intend to get another sponge filter up and running soon!)

Then finally, what is the best way to keep a tank clean? Going bare bottomed hasn't worked for me in the past ((I tried it for a week with my original trio when they moved out into their summer tank, and they were so unhappy with it that I ended up racing out to get sand before they mutinied) but by the same token, there's still a heck of a lot of gunk in the big tank as the vacuuming didn't get all of it (nor did turkey basting *facepalm*- see the pics).
Would I perhaps be better off changing out my substrate and replacing it with new stuff? (As Pete and Izzie are a leucistic and goldie respectively, switching to taihitian moon sand would be AWESOMEEEEEE....that is, if I had the cash...)

Anyway, many thanks in advance!- Minnie/Caitie

 

[iChris]

Try putting the bottom half of the internal power filter into the leg of a pair of stockings, and secure with a rubber band, this will only allow very fine particles to pass to the intake.

as for your water, I think that the air powered filter could be having trouble coping and achieving adequate biological filtration.

 

[Minniechild]

Thanks, Chris! Sounds like a plan, and should *hopefully* get me out of trouble! *Goes off to find rubber bands*

 

[iChris]

just keep in mind that rubber bands may perish and go brittle after some time in water, so keep that in mind.

 

[blackdog]

re cherries.

The filter will be the least of their problems. Once the axies go in, the cherrie will be eaten up pretty quick once your axies work them out

I had one or two last a few weeks, the bulk got snapped up in the first few days.

Bren