How to treat hard water & low pH when live plants?

[jodacro]

This is a twenty gallon freshwater tank with 13 fish (tetras, angel, catfish, sucker) and live plants: long stem with long speared leaves, grassy and low dark-green medium-sized leafy. The long stem plants have been deteriorating (leaves thinning, color fading, losing fabric) and the other plants aren't really thriving. I've tested the water with Tetra Easystrips and it indicates that the water is "very hard" and pH is low. I'm pretty good about swapping out ~15% water every two weeks and the new water going in has been treated with "Proper pH 7.0" (by Aquarium Pharmaceuticals) and "Stability" (by Seachem).

Other points, I recently:
* upgraded lighting (fluorescent) from 17W to 20W but I think I may need stronger. Plus, light is on for ~12 hours/day now.
* got rid of under-gravel filter
* did away with water aeration
* removed gravel and put in iron-rich substrate

Questions:
* How can I soften the water without hurting plants?
* What about pH?
* Do I need stronger lighting?

[KingFisher]

Hi! Firstly, test strips are notoriously inaccurate, so I recommend that you go get a liquid test kit with the test tubes. API makes a good one, but there are others as well. Before trying to adjust anything about your water, you need to know the exact levels. You may find that your water is in fact fine for your plants and fish. It is uncommon to have both a high degree of hardness and a low ph at the same time. This is why I think you may not be getting correct readings with your test.
Second, the use of ph altering chemicals is not a good solution, as they can be responsible for ph swings which can happen fast enough to cause harm, or even in some cases, kill your fish.
Thirdly, a 20 gallon tank is not a suitable home for even a single angelfish. They get big and need more room. What kind of catfish and sucker do you have? several of these are also unsuitable for a 20 gallon tank.
Many of your fish come from water that is lower in ph, so your water may be fine for them. Many fish can adapt to water with different ph and hardness levels than their native waters. Your hardness may not need to be adjusted.
Please let me know your exact water parameters with a good test kit and it will be much easier to figure out what steps, if any, you should take to change them.
KF

[Alfcea]

Hello,

I totally agree with KingFisher. However, if even after us trying to make you change your opinion you still want to modify your hardness, then the one option would be to dilute your tap water with either deionized water, rain water, distilled water... or make use of reverse osmosis. Please note, however, that these methods will also eliminate other nutrients from the water as well. This may affect any plants you may have.

Another option I can think of is the use of chelating agents. Many water conditioners like TetraAqua's AquaSafe contain chelating compounds that will "inactivate" heavy metals. They will also inactivate calcium and magnesium ions therefore making your water "softer". Please note that the chelating agent will not eliminate the calcium at all. It will just "inactivate" it.

[Lady Hobbs]

I think you should be more concerned right now in homing your fish properly and seeing to their needs than worrying about plants. I would be thinking of buying proper liquid test kits, a larger tank and thinking of the pH needed for the fish. You mentioned removing aeration. Is there a reason for that because fish need aeration and especially if your tank is overstocked.

You will have to buy better lights for a planted tank. Some low light plants might work but really, make the needs of your fish come first before getting into planted tanks.

[jodacro]

API test kit results:
pH : 6.2
Ammonia : 0.2 ppm
Nitrite : 0
Nitrate : 40 ppm

Purchased:
- 28W fluorescent light (from 17W) -- better but still not enough.
- Yamato Green aquarium plant fertilizer.
- Another plant: driftwood covered in Riccia Fluitans

I'll get a bigger tank in not-too-distant future but, in short term, I want to help better the existing 20 gallon tank.