How much of an increase depends on how quickly you change the water (I'd drip change for smaller tanks). Your substrate will begin buffering the water as soon as you start changing it, so the slower you change, the more time you give it to keep up.
I don't like buffering substrates because they are expensive and require a tank teardown every year and a half to two years, but as Zoidburg mentioned, it will make your life a lot easier if you are just starting out. For smaller tanks, the cost might be worth it.
Personally, I don't care about pH that much, but if I did, I would pretreat my water with peat moss and then remove any tannins with a resin like Purigen. That's exactly what Diana was doing for her tanks, and peat moss actually lowers TDS unlike driftwood, IAL, or cones.
Tds its not always what ppl think, it contains all debris in water column, its not always about minerals, If You have really high TDS, add extra sponge filter and You'll see how dramatically TDS go low. Your params can be right, but if filtration system suck, TDS is huge
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