leaking tank and pH Hardness conundrum

[allan.mcdougall]

I have a 10 yrs old community freshwater tropical tank, now leaking . Not a huge leak but obviously I am concerned that it will burst open at some point. I have a replacement 180 L tank purchased online but due to covid it will be a while before I can get it couriered. have lowered the water to one third level which has slowed the leak. Any advice in the meantime? When the nw tan arrives, I would like to get the fish in ASAP Can I use the gravel, water and the plants from the present tank to kickstart the new one?
I also have a longer term issue. I use rain water collected from a steel roof which has Ph 6.6 -6.8 KH is only 1-2 Yet the tank maintains a Ph of 7.2-7.4 occasionally higher, and the Kh is around 4 The tank is planted but not densely, and there is no new substrate, limestone coral shells etc. There are some hard rocks been in there 10 years and one pice of wood also in there 10 years. No ornaments. External canister filter 600ml/hr No CO2 set up.
Any nexplanations? THe ph and kh kits are several years old. Arer they still gong to be reliable? Thanks Allan

 

[JuiceBox52]

To help kickstart the new tank in its cycle use the filter media and gravel from the old tank

 

[Metalhead88]

Just move everything over .... The gravel, filter, decorations, some water for fish to swim, and lastly the fish and then fill it up all the way. That's equivalent to a big water change and the tank is cycled.

 

[allan.mcdougall]

To help kickstart the new tank in its cycle use the filter media and gravel from the old tank

 

[allan.mcdougall]

thankyou.

To help kickstart the new tank in its cycle use the filter media and gravel from the old tank

 

[JuiceBox52]

No problem