Water quality - RO/DI help

[Macfish]

Hello all, first time poster, small time hobbyist.

Background: 55gal fresh water tank with 2 small pieces of driftwood and 2 live plants. Regular stone/gravel substrate, a few pieces of slate and a bubble wall about 1ft in length.
Eheim 2236 canister filter with “stock” filter media minus the carbon pad (replaced with floss).

Tank has been set up since July (6+ months). Fish include a few killies, female betta, two pictus cats, a few tetras, 3 angels and a pleco.

Water quality

Tap Water 1-26-08
PH: 7.4-7.6
Ammonia: 1.0pm
Nitrate: 20ppm
KH: 4-5dKH
GH: 10-11dGH

Tank Water 1-26-08
PH: 6.6
Ammonia: 0.0ppm
Nitrate: 80ppm (2days after 20% change [24th])
KH: 2dKH
GH: 12dGH

I have not seen ammonia or nitrites in 4+ months however, no matter what, my rate’s are always 50-70. I do weekly 20% water changes with aged-heated-aerated tap water. But after reading up on the matter and doing the math myself, I know this is a tap water issue that will never go away.
So I invested in an RO-DI system (100gpd – nice unit)

RO-DI Water 1-26-08
PH: 6.6-6.8
Ammonia: 0ppm
Nitrate: 0ppm
KH: 1dKH (might be 0)
GH: 1dGH (might be 0)

Goal Water
PH: 6.8-7.0ish
KH: unknown since it has little effect on the fish, but I want stable PH
GH: around 10 or so

I know KH & GH are linked and normally adjusting one changes the other… not a problem… and that raising the KH/GH will raise my PH slightly… not a problem… I have a product from Kent Freshwater (RO Right) - are there any other products I will need? The RO Right raises the GH and adds minerls back to the water, will the RO Right increase the KH also? or will I need something else for this? I plan on using a 15gal container filled to 10gals and power heading the treated ro water out to the tank (heated). Also, once my goal water is obtained, would there be any adverse effect in regards to changing from tap water changes to ro water changes of the same 20% weekly?

 

[Lotus]

I believe RO Right will increase both GH and KH, and pH too.

It should be OK to switch between the two, as your tapwater has fairly low KH and GH anyway. An alternative is to mix RO and tapwater at the same ratio every week. That way, you'll get some of the minerals from the tapwater, but lower nitrates. You probably wouldn't have to use RO Right if you're mixing tap and RO.

Do you know what your tapwater nitrates are, or do they vary from week to week?

 

[Macfish]

My nitrates pretty much always stay in the 20ppm range.

 

[Lotus]

Well, if you do a 50/50 or a 75/25 mix of RO/tapwater, you'll at least reduce those nitrates. If you add a bunch more plants, you'll probably have nitrates of 0-5 ppm by the end of the week.

If you bump up your water change percent to 30-50%, the nitrates will drop fairly fast, too.

 

[Macfish]

I've never been much of a green thumb, the sword I have is doing so-so, the hornwort is hanging in there I guess, its not very manageable tho and loses alot of its needles making a mess.
I guess I could take any of those topics over to the plant section and get input there (reading those posts) or get input from you through PMs or something.

I tried the RO right lastnight at 1tb spoon per 10gal with a power head going and a few hours after my API KH&GH tests still showed crap for numbers. Maybe 1d for each. After reading up on both the test and the product it seems it might just be the test kit only testing for X instead of X&Y.
Does anyone have any dealings with Kent FreshWater RO-Right and or API's KH&GH tests that could shine a little light?

Lastly, your tanks are breath taking Lotus!

 

[Lotus]

Hmmm... I went and read about the RO Right and its notes on GH and KH tests. It seems that the product doesn't recommend using more than two teaspoons per 10g, even if tests read "off."

I'm not sure what to say about that product, although I know many people are happy with it.

This article has a lot of info about the pH/GH/KH relationship, that might help you: Aquarium Chemistry, pH, gH, and kH relationship

Thanks for the compliment! The site desperately needs updating