Hard Water Area Shrimp Tank

Hi all.

I have done enough research for everything I was certain about to be directly contradicted hehe my head is spinning.

I want to start a heavily planted low tech shrimp in my cycling 20 gallon tank (aqua one 620), with peat to lower hardness and sand as the top. With the shrimp i want to learn to learn to raise fry, hopefully from my bristlenoses and after a long time/when i feel confident, i would like to raise rainbowfish from fry or eggs.
plants i am thinking of are jungle val, crypts, water lettuce, penny wort, Christmas moss, java fern  plus stuff that have survived me in the main tank i don't know the names of.

My water test results in my main tank are nitrogen about 30 (lower than the water supply), ammonia 0 and nitrite 0.

The shrimp tanks has aqua one filter and a small internal filter.

I live in a very hard water area I don't understand these numbers and don't have a test yet.
my local water according to my water suppler  Jan to March 2016
Total hardness as
Calcium (mg/l)   Total hardness as 136
Calcium carbonate (mg/l)   Total hardness as  340
Degrees Clark (°Clark or °e)   Total hardness as-23.664
Degrees French (°f)   Total hardness as 34
Degrees German (°dH)   Total hardness as  19.312
millimoles (mmol/l of Ca) -3.4

Nitrate from 31 to 34.8   
pH value 7.55 to 7.86
           -------

My questions are
As i am relying on plants to remove nitrate how frequent should water changes be, little and often or 20 -30% once a week?  since i raise the nitrates each water change.

Do I need peat layer, then gravel then sand?
can poison air pockets in sand be avoided if sand is 1/2 an inch to an inch?
do i need to add supplements in with the peat? i want to avoid anything chemical other than safe plant feed.
how long till peat is inert?
Is this a daft way to do it? i want maximum plants v low set up and running costs
Will accidentally dropping the small filters sponges full of live gack seed the built in filter faster? I feel something good should come out of that mess!

liquid rock lmao Colinb
Thank you, rain water makes sense, it is tricky for me get as i live in a flat with out a garden, I was hoping to avoid RO water, since the water I have is restricting what i can keep I shall just get used to the idea

How about peat and plants do they get something extra from it?

My water is also quite similar (17^odH) and I have amano shrimp in 3 of my tanks. They seem to be doing quite well and have grown (and moulted) quite a lot in the few months that I've had them. The tanks are all planted, but not very heavily, and the shrimp share the tanks with a variety of fish, from which they take no messing when it comes to the food. 
The largest ones are in the my temperate tanks and they are quite bold. I have to admit that it was quite a strange feeling to have one run up my hand when I was cleaning the tank. 

If you're using garden soil make sure the source isn't contaminated with pesticides or herbicides or that it hasn't had fertiliser like growmore granules added to it. Good luck 

Thank you for your replies,
Got my gravel they didn't have soil based soil compost or 1mm gravel oh less it was in primary colours (within distance i was prepared to cycle with gravel) I got gravel and sand because they had it and want I to set it up today, i was hoping to get 1mm gravel like Fiona uses.
i have MTS already in the both tanks so sand would be moved about. I watched a vid on you tube last night about impulse buys clearly that didn't sink in.

I live close to an ancient deciduous woodland, there are many areas very steep with rain eroded bits,
what do you think if i use that as the thin soil layer after baking it to kill any nastys?

I am certain nothing chemical has been used for very long time if ever. As shrimp eat leaf mould it seems to me perfect. i thought the steep bits too make sure no animals have left any ammonia rich patches

Any thoughts?

Hi Fiona,
I did look the prices online and the cost of postage was more than cost of products.

The soil i used was from over 6 inches deep, no leaf skeletons, it is long rotted dark brown with some sand and small pebbles, i thought the same so i went below the rich spongy layer. I got soil from area of oak and beech trees both leaves are said to be beneficial to shrimp, they have similar effects to Indian almond leaves.
I think I will buy the compost next time when i see  what i need, now that i have a better idea about it, i would like to do dirt based on main tank too, that will be less impulsive.

I put in about half inch soil, then gravel, then sand. Next time i will do it very differently hehe
My plants came Saturday, I split them between both tanks, in the dirted tank the plants didn't seem stop growth to settle only 4 days and each plant has good new growth, main tank's plants had first signs of new growth yesterday.

If there is an algae bloom i will have learned a big lesson hehe, I am already itching start over again following Walstead method, that i heard about an hour after i set up the tank!

hehehe that makes sense
i will leave it till i have everything next time
plants are doing well so i am happy
and i get good idea of how a dirt tank works and what colour water will be

Oh, even when I mess up hehehe
hmmm ok since it is the law lol

This is dirt then stones then sand 
soon to be dirt sand gravel hehe
the cambomba stuff has grown 4" in dirt tank and 1.5 in the main, all plants are doing much better in the dirt, except the penny wort that has not recovered from planting in either tank.

2 weeks I can get the right stuff, on the plus side i learnt lots and the filters are cycled

I think 2 of my BNP are male, they had an argument over food yesterday, aggressive posturing I think as neck hooks weren't out except in threats, it lasted about 90 seconds and then the smaller one who looked he started it all backed down. If there is another fight i will move one in to dirt tank, I hope there is no more drama with them till I have redone the 20gal . The bristles are less than a 1/3 of size the other male, the one I am sure is female has no bristles on her nose only on her cheeks. I found somewhere online that males in company of other males can develop slower but alas now i cannot find that reference.

Very good. 

Interesting that you mention the pennywort not doing well - mine is starting to turn very brown (although I'm about to establish whether it's algae or rot).

Thank you

Very good. 

Interesting that you mention the pennywort not doing well - mine is starting to turn very brown (although I'm about to establish whether it's algae or rot).

My penny wort in dirt tank went brown too, some leaves dissolved, now after 13 days since planted, it has spouted 3 new leaves and that was a small piece separated from main plant, the large penny wort in main tank has also started putting out new leaves, i can't see any brown on it or bits dying off now, i think the snails must have had that. looks like it has about 5 new leaves, it is a hard to see area, it is over 6x the size of the other one and had main root stock on it.

Is your penny wort new? might be slow to acclimatize, I hope it recovers