high pH

[Eaesko]

I have a 34 gallon cube filled with plants as you can see.
it is 3 months old, 110 watts of 6700 k power compact. the pH is hovering around 7.8-8.0
I am wondering how i can lower it. I have just installed a RODi system in my house because i was thinking that my tap water was the issue. some of my plants which need lower pH aren't doing very well, which was my cause to seek more help. Any suggestions?

[somewhatshocked]

What's your substrate?

What are you using to remineralize your RO/DI water?

Other parameters? KH, GH, et al

[GeToChKn]

I had a variety of plants in my tanks from 5ph to 8ph, and ph was never the issue if they didn't do well. Ferts/co2(carbon source)/light.

[Dx3Bash]

I assume you are using pressurized CO2 since you have a drop checker in your tank. Are you adding fertilizers and root tabs?

I use RO/DI because I was tired of fighting 8.6 pH tap water with a hardness reading between "liquid rock" and "can scratch a Diamond". I also intend to start a large Discus tank soon with 50 or so Cardinals, but that's another story. Make sure you remineralize your RO/DI water. I use GLA GH Booster and Baking Soda. You can also just simply use some tap water mixed back in with your RO/DI water. Make sure you test to find the desired ph/gh/kh you desire. Also, make the changes gradually. It will be easier on your fish and plants to adjust.

Good luck.

[Eaesko]

yeah i use pressurized CO2, add florite, and adding some iron and potassium as needed. used florite substrate. i need to get an iron test kit tho i think its pretty low because some of my sword leaves are turning yellow.
what do you guys mean by remineralize the ro/di water?

[Dx3Bash]

RO/DI units completely strip everything out of the water, including nutrients and minerals which are healthy and necessary for fish and plants. In addition, because RO/DI water is void of any buffering ability you are susceptible to possible large pH swings, etc. which can cause larger problems. So what do you do? Simple, you will need to raise the GH/KH back to safe levels and add some of these minerals back into the water to make it safe for fish and plants. Suggested products to use for raising the GH are GLA GH Booster, Barrs GH Booster, Seachem Equilibrium, and to a lesser extent Kent RO Right. To raise KH, simple baking soda. To determine how much baking soda to use, this calculator can be used: http://www.dataguru.org/misc/aquarium/calKH.asp

As previously mentioned, you can also simply add some tap water to your RO/DI water to "remineralize" it. I would suggest testing a 3:1 ratio and adjust accordingly to the parameters you desire based on the fish/plants you keep.

[homemadepopcorn]

Just do a test with different mixtures of RO water and your tap water and see what ratio best suits your needs.

[Zorfox]

I agree with GetoChkn. What are your nitrates? I'm guessing 0. Sounds like a nitrogen deficiency rather than iron since you're already dosing iron and using flourite substrate.

[somewhatshocked]

RO/DI water is 100% pure, meaning there are zero dissolved solids in the water.

You have to add minerals back to the water - either with dry minerals - or some sort of liquid solution. There are all kinds of products on the market that allow you to remineralize to the specific KH and GH you're aiming for.

Originally Posted by Eaesko

what do you guys mean by remineralize the ro/di water?

[Diana]

If the tap water is OK, just hard water (high GH and KH) then try blending RO + Tap. Then test to see if the GH suits the fish.

If the KH is anywhere near the GH level, then the pH will also highly likely be in the right range for the fish.

If you are keeping black water fish, then I would filter the blended tap + RO through peat moss to add the organic acids these fish like. This will probably drop the pH a bit more.

If you are keeping rather adaptable fish, and it is the plants you are worried about then research the plants' needs. There are a few specialty plants that really do require low mineral levels, and the resulting low pH. Aim to keep these plants happy, and the other, more common plants will usually adapt.