How to change soil substrate in cycled tank

[Goco]

Hello guys, 

currently i have Tropica Soil Powder Substrate in my tank, which doenst buffer my PH. Its constant on 7 PH. Im using RO Water with Salty Bee Shrimp GH +. 

my question is:

- can i put some new Ebi Gold Shrimp soil substrate in the corner? Could this hurt the Tank? How should i replace my old Soil?

- Maybe put the new soil inside a cup and than in a corner of the tank? to buffer the PH? could this be working?

[sdlTBfanUK]

Some breeders put the substrate in a container and then put the container in their tanks, but it obviously depends whether you can stand to look at it like that, I couldn't myself, but they do it to make changing the substrate really easy! By just doing a corner the substrate won't last as long as doing the whole tank properly so it will work, but it just won't last for long. The more buffering substrate there is the longer it will remain steady so you can't  improve on replacing the entire old substrate. It may be possible to put the new buffering substrate over the top of the old substrate if the old substrate isn't very deep, but again this really isn't going to gain you anything as you are still going to need to re layout/scape the tank, so you may as well remove all the old substrate anyway? 

There really isn't any shortcut that will mean you will have a nice looking scaped tank that won't need to be done again soon and a small amount like a cup full will need replacing often and likely cause swings in the parameters! As long as you keep the old water in buckets with all the bits/filters/plants etc in it, it shouldn't take more than a week for the cycle to sort itself back out I would expect using as much of the old water as you can? 

Simon