Tap water is allowed a little bit of ammonia, it might indicate you have chloramine rather than chlorine in it. You just need to make sure that you're using a dechlorinator capable of removing chloramine and detoxifying the resulting ammonia. The filter in the tank should remove the ammonia from the tap water in no time once matured.
Plants will also consume ammonia first which is another reason they're good to have. Think of them as an extra buffer for your biological filtration
Keep adding the food, looks like you're nearly there.
Even in theory though you're self-sufficient tank wouldn't be sealed so it's only got to be partially sufficient. I assume you'd still be adding light, food, heat and a pump for circulation.
With a large circulated, heavily planted tank (maybe 100 gallons) with a low enough stock level you can remove the traditional filter all together. Plant growth will remove the ammonia, nitrite and nitrate. Problem is there are also hormones from the fish which in nature are rinsed away over time before eventually breaking down. So you could set up a high tech rain-water powered water change system perhaps, but you'd need an active carbon filter on the rain water to remove contaminants or a much larger tank and lower stock level - unless you live downwind from nowhere.
Then there's the minerals that the fish use from the water, in the wild these are washed into the water from surrounding earth and rocks. Without them the water could get softer and softer over time, then you get "old tank syndrome" the fish growth is retarded, deaths and sickness and then the ph crashes and the whole tank is dead.
Perhaps if you had a river on your land you could pump the heated river water into the tank 24/7 and overflow back to the river. This might be the best way to have a fairly maintenance free tank - you'd still need to look after the pumps and you'd be at the mercy of any local contaminations.
So I guess I don't know but it's an interesting idea.
for my large marine tank I used to premix the water in a 150L vat, heat and aerate it and pump it into the tank after syphoning out the waste. The whole water change took 15 minutes then I'd turn the RO tap on and refill the vat, add salt and it was ready for next week. Other maintenance and water tests took a lot longer. I use buckets for the 220L tank but 40L change takes me about 15 minutes again. I mix the water up the night before which is another 10-20 minutes but then I use RO and lots of different additives to get the exact water parameters.
It really shouldn't take a long time and if you have low enough stock levels 10-15% water change should be enough.
To get a completely self sufficient tank you're looking at massive quantities (like lake) and careful stocking and plants. Most "cleaning" fish actually pollute more than they clean turning algae into poop for your filter and water changes to remove.
Removing the brace bar seriously weakens the tank putting more pressure on the front and rear panels as well as all the joints. They don't add them in for decoration you know I'd seriously consider putting something back to help re-enforce it.
just a quick paranoia note about shop bought RO water.
We've had several people suffer tank disasters where for whatever reason the shop bought RO water was not what is was supposed to be.
Either the shop did not maintain the filter and sold tap water as RO water or when adding minerals or marine salts got confused and added the wrong one or the wrong quantity. I'm sure you can imagine the devastating result of doing a 20% water change with seawater in a freshwater tank!
For this reason I always recommend that people only buy pure RO water and mix the minerals they require themselves. For this to work you need a few things. 1. A TDS meter. This measures the total disolved solids in water. RO water should have 95% of the TDS of the tap water removed. Tap water should have less than 500ppm TDS so anything over 25ppm TDS has not been properly filtered. The tester is a pen style device that you dip in the water for an instant reading and costs less than ?20 from ebay. If the lfs sells RO they should be able to show you the TDS with their tester - but it's a worthwhile investment if you're using RO water. If the RO water is DI filtered then the TDS should be zero, this is ideal as without the DI filtering the RO water can still be quite high in phosphates which encourage algae. Getting back to the point, you need to use a TDS so that someone elses error doesn't cause you problems.
2. A KH/GH test kit. So you know where you are. Initially you'll be doing multiple tests on the premixed water as you add a bit of tap, a bit of minerals and a bit of RO again and again working out the right ratios to get the water your fish need. When you the mix right a 10% water change one or twice a week with that and testing the tank weekly until the PH, KH and GH are where you want them. Then just a test once every week or even fortnight to ensure that things stay level and where you expect.
3. Minerals. You can only get so far mixing RO with tap water, you can change the density of minerals in the water but not the ratio. My tap water has currently 7dGH but 15dKH approx. As I understand it this is due to lots of chalk and very little magnesium. To get this to 4dKH and 8dGH I need to dilute it quite a lot and then add TMC Pro Discus. To keep this acidic I then add blackwater extract and keep a CO2 canister running with a PH controller.
Anubias, Moss and Java Fern are normally bought attached to rock or wood. If not they're bought loose then attached to something with a little fishing line. They don't root into the gravel so don't need any nutrients there. If this is all your going to add then root substrate would be a waste of time and money.
Plants that do root into the gravel like Cryptocornes and pretty much 99% of everything else should get the substrate nutrients either through a product like eco-complete (that's not a recommendation btw, I don't currently have a favoured substrate) or root tablets put into the gravel. Ideally they'd have both, the tablets recharge the nutrient rich substrate. So having it really does increase your flexibility and chances of success with more species.
Part of the problem is that many great plants like the Amazon Sword and Vallis will grow far too large and swamp the tank and many of the smaller ones like Hydrocotyle sibthorpiodes require a lot more light than you have. That said new plants are being introduced every week and even with just the few currently suitable you can still have a great looking tank.
For cherry shrimp and a planted tank I'd leave the PH alone.
Plant species that should work for you include: Anubias Nana (small leafy plant often attached to bogwood - no need for root nutrients) Christmas Moss (a dense moss that covers surfaces with a little encouragement and again needs no root nutrients) Java Fern (a taller plant for the background that's easy to grow in lower light conditions - again root substrate not required) Cryptocorne (many varients available but it's an easy grow plant that should do well and spread out. It will benefit from planting substrate)
Those should get you started off, I selected those as they're commonly available and fairly easy going. Have a look at whats in the lfs too. All proper aquatic plants should carry a care label telling you the scientific name, light, temperature and PH requirements plus the height they grow to.
meri wrote: I have read mixed information about the length of the cycle as some posters say 10 days, others 6 weeks. I thought once nitrite/ammonia are zero and you have nitrates, it's all done?
Yes that's pretty much the sum of it. It's hard to put a time scale on nature and it depends very much on the bacteria colony that you start with. If you manage to get a little mature filter media or a cycle product that works like biospira then the cycle time can be very short. If you're starting in a clean tank in a clean environment though it can take longer for the bacteria colony to form.
There are so many factors that can alter the results but without mature media I would not expect it to take any less than 21 days and 28 would be more likely. The ammonia eatign bacteria takes 5-10 days to colonise and start producing nitrite. Until there is some nitrite the nitrite eating bacteria don't start to grow and they tend to grow at less than half the speed of the ammonia eating bacteria.
Some people have not been so lucky and it's taken 6, 8 or even 12 weeks. Fingers crossed it won't take that long for you but it takes as long as it takes. As you said, you just keep feeding and when the ammonia and nitrite hit zero you're done. Do a few water changes to get the nitrates down again, keep feeding for another couple of days to ensure the results weren't a fluke and the readings stay stable and you're all done and ready for fish