RO water changes

trapperwolves

My current tap water has a GH of 3 and a KH way off the charts at about 16. I am using RO water with a small percentage of tap water to keep the KH at about 5 when I do water changes.

Should I be using a product such as Seachems Equilibrium for RO water or is tap water (mixed with ro) usually sufficient to supply the minerals needed for fish and plants?

Thank You

Byron

A mix of tap and RO will do the job, though it will also lower the GH and a GH at 3 is good (for soft water fish).

I assume you are using RO to try and lower the pH? If you respond, could you indicate the pH of the tap water and what you want for pH in the tank? I might have suggestions.

Byron.

trapperwolves

When I set up my 29 and 10 gallon tank I used water straight from the tap not realising the kh (16) and gh (15) was so high. I knew I had hard water but did not do any testing to determine the results. The ph of my tap water was 7.8. I have since installed a water softener which brought the gh to 3 but left the kh at 16. I have also installed a RO unit and have been very slowly doing small 16% (twice per week) water changes using almost 100% RO water. I tried not to change the water parameters to drastically or to quick.
As of yesterday the water in both tanks are gh-4 kh-6 and ph 7.5 and 7.4. The tanks were originally set up with plastic plants. I have since made the switch to real plants and I was trying to adjust the water parameters to induce plant growth and health and also help the well being of the fish with better water conditions.
I was afraid that by recently using almost 100% RO water I might be robbing the plants and fish of required nutrients that are not measured by gh/kh readings.

As a side note--ammomnia 0 nitrites 0
nitrates 15 ppm for 29 gallon tank
nitrates 10 ppm for 10 gallon tank.

Thank you again for your response.

Byron

I obviously should also have asked what fish species. Plants will be fine with what you now have, and the pH may lower naturally. Fish are more critical pH and GH wise. The KH itself has no effect whatsoever on fish or plants; it is its role in buffering pH that is important.

At this point I might just let things stabilize and monitor pH somewhat regularly (every few days if no changes, more often if you see it changing). KH can be removed by boiling the water; this boils out the carbonates. I've never needed to do this, but another member did and reported some interesting results where the GH rose a bit. You might want to try this to lower your KH. I've no idea how much boiling this takes. One of these days I intend to do a bit more research on this aspect.

My GH and KH out of the tap are < 1 d and for all I know may be non-existent. This is fine for my soft water fish, most of which are wild caught, and with two exceptions the plants are fine too. Vallisneria grows but not well in my soft water, and this doesn't bother me because I knew this when I got some Vallisneria to try. But my swords are now having troubles with calcium deficiency, and this causes them to take up too much iron, and iron excess slowly kills the leaves. Following Diana Walstad's advice, I am attempting to raise the GH to around 4 d. I used to use dolomite in the filter to deal with this, and it worked very well; the pH stabilized around 6.2-6.4 and the swords were lush and green. I can't get dolomite locally any longer, and have tried aragonite in two tanks but the pH is rising to 7 and 7.2 which I don't like, so I'm still fiddling. In a third tank I am resorting to Seachem's Equilibrium. I will go with the method that works best once I've monitored these for a few months.

Byron.

trapperwolves

Thanks for your recommendations. Most fish I currently keep are livebearers except for some corys and a pair of gouramis that will hopefully be mating soon. I believe the water parameters are finally were I need them (or getting close to it). I will just have to figure out how much RO water to mix with my tap water to keep the water parameters moving in the right direction. Right now I'm thinking somewhere around 80% RO and 20% tap water should keep my gh/kh and ph were they need to be. I'll be mixing up some formulas and taking some readings to find the exact proportions necessary.

Good luck using the Equilibrium and I hope you're able to bring your ph down to where you want it. I am actually going to be receiving some Villisneria for free this weekend and will be attempting this plant for the first time.

It's a shame you don't live nearby as I would gladly be able to supply you with all the hard water you would ever need. I shouldn't complain though as from what I am learning it is much easier to make hard water softer than the other way around.

Good luck again with the Villisneria

Byron

Your livebearers will do much better and be healthier with water straight out of your tap (before the softener). They need medium hard or harder water, and pH above 7. I would not soften their water, the mineral loss will affect them internally.

trapperwolves

I will have to mix ro water with my tap water to keep the kh at 6 gh at 4 and ph at 7.6.

I'm thinking these parameters will be OK for the livebeares as well as the plants.

Thank you again for your input.

Byron

GH at 4 is soft water. Livebearers require medium hard to hard, I would suggest no less than 9 GH, as noted in our profiles of the species. Mineral in the water is essential to these fish, just as no mineral is essential to many soft water fish.

trapperwolves

I will start slowing adjusting to a gh of 9. This typically means also raising the kh as well doesn't it?

As usual thank you for your input.

Byron

I've never bothered with KH. When I had livebearers (and my tap water is near zero GH and KH) I just used dolomite for the substrate. Aragonite also works. Using it in the filter is easier, in a mesh bag; it only takes a bit.