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gh/kh/ph tank vs tap questions

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Hello all
I'm writing about a 20gal low tech Excel based planted tank thats been running for 3 years or so. The plants do OK. Not a ton of growth, but some. A good deal of leaf melting in older leafs. I've fought my share of various algae but seem to have it under control at the moment. fingers crossed!

50% WC every 7-10 days
2x AquaClear 30gal filters. no charcoal.
2 water circulators
no air stone
48W T5 HO 6500k 8 hours / day. a little natural light too
Excel, Potassium, Iron, Trace at recommended levels.
1TSP Equilibrium /month
root tabs every 4 months

pH 7.0 - aprox. it swings between 6.8-7.2-ish.
Amonia 0
Nitrite 0
Nitrate 30-80ppm
KH 2 *seems low?
GH 2 *seems very low?

Tap 8.5 pH
1-2 GH/KH

The main reason I'm posting, is because I recently got myself a Python water siphon. It definitely makes life easier, and the tank seems really clean these days. Algae is down too. But still, the plants aren't thriving.

Do I need to lower the 8.5+pH from my tap, or can I just add it straight? (I still use Prime) Will my tank naturally lower the pH over the next day or so? It seems like a shock to add 8.5ph to a 7.0 tank, and I don't think I want the pH in the 8+ range... right?

For the longest time, when I was doing buckets, I was conditioning my tap water with Acid buffer to bring my high pH tap water (8.5+) down to a reasonable level. However, in doing so, I'm not helping the already low KH levels. I suppose I could use Alkaline buffer to increase KH, but that raises pH, and its already high in my tap water.

Trying to help the plants out... I've been told I should raise KG and GH. What are good ways to raise those levels, and how to do keep the pH in check while doing so? (I was shooting for a target 6.8 for the ph but I know that can be flexible)

How does one do this??
What else could I be doing to help out in this scenario?

Did I provide enough info / make sense here?

Thanks for the feedback everyone.


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I would forget about the pH for now, at least, and just add tap water, untreated. Water companies add chemicals to their water to raise the pH to avoid corrosion of the copper and/or lead plumbing in houses. Usually that increase in pH is very temporary, so the pH drops naturally. If you do only a 50% water change you will already be dropping the pH at least a little below the tap water pH. Generally Seachem Equilibrium is added when you do a water change, not weekly (unless that is when you do the water change.) You may have enough light that the plants are short on phosphorous, which you aren't dosing, so I would dose that too, along with the other nutrients.
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