I'm very new to hydroponics and new to growing plants in general. I'm having some trouble with my first experiment into hydroponics. I have an areca palm that looked great when I bought it two weeks ago, but has since turned yellow/brown mainly at the tips of some leaves, but some entire branches. The stems have also gotten weaker.

I've learned that during the first week I was doing things incorrectly. I was using filtered (hard) tap water and only pH balancing to about 5.5-6.0 and adding nutrients. Then, each day I would add more pH balanced tap water (without nutrients) to keep the level up. This past week the plant has slowed its demise, but is still getting worse. I replaced all the water with RO water and added nutrients. (It was balanced at about pH 5.0-5.5 after adding nutrients, without adding pH adjusters.) I'm now letting the water drop to about half-full (when about 4 of the 9 liters of water is gone) before I add more. If this too sounds wrong, please let me know.

I've kept track of the pH and ppm of the water during this past week. It has remained at a pH of about 5.0-5.5. The TDS started at about 405 ppm and has risen to 470 ppm while the water level has gone from 9.0 L down to 7.4 L.

I've posted some photos of the plants:

{{gwi:1013017}}, new

{{gwi:1013018}}, one week old

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Any help is greatly appreciated. Thanks.