I'm sure this is confusing, im not a writer....oh and please feel free to tell me im wrong.=newbie.
i've 150 litre tank since december with an inch and a half of white gravel,
i was vac-ing the water into a 15 litre old clean bin then putting the bin up higher than the tank and leave it for two hours to let it settle, then carefully siphen 80% back in again i was doing this after my tank cycle had completed.
i got 3 new fish, then my nitrates spiked (i forgot to check of them for 2 weeks) i got scared and then stopped doing deep cleaning and recycling the old water,
then i got a catfish who leaves such a mess i was doing 20 litres purely superfisious gravel cleaning a week just to keep it looking ok, did this for 3 months(no deep cleaning)
now there is so much small dirt and new hard water in my tank im getting lots of problems.
if i was to do a proper clean i would have to loose 50% water a week. (thats alot of tap safe. cha ching)
now that i havent done deep clean, my tank is infested with everything (bad LFS's in dublin city center does not help)
hope that makes sense, im going back to my old ways soon.
now im far from being an expert, december is the first time i ever had a fish.
but if u check your amonia , nitrite, and
especially nitrates levels
i would say you could get away with a 5 litre water bottle (maybe 2 of them)(or a water dispenser container, the type u get in the work place)( u can see the dirt settle) a clamp on your vac, and another tube to siphen back to your tank.
as long as u have a api master test kit your should be ok.
you will still need to do a small % water change but not as much, which i think has been knocking the hell outa my fish (new apartment block, who knows whats in the pipes).
hopes this makes sense to read , oh and again please feel free to tell me there's more than just nitrate and visible poo to get rid of in old water.