Best practical way to lower GH/KH for tropical fish

[Newbfishlvr]

My PH pen and GH/KH API test kit came today, and I was shocked at the results. I have been using the API test kit for both of my aquariums 75 g and 150 g. Ammonia and nitrite always 0 for both, and Nitrate ends up being about 10-20 by the time I do my water changes (I test before each water change to see where I am at). Water changes are typically 50% every 7 to 10 days, more or less depending on what my Nitrate ends up being (I don't let it get above 20 but if it's 5 i'll put off the change or do less without suctioning gravel).

My results were 18 dGH, 7dKH, PH 7.8 in 150 gallon and PH 8.0 in 75 gallon. I have tap water sitting out to be tested tomorrow. My fish have never had a problem, very large and do not appear to show signs of sickness but from what I have read I need to lower it to prevent organ damage. I would also like to soften the water with hopes of keeping more tropical fish such as angels, tetras, etc but undecided.

Here is my question, what do you recommend?

1) Reverse osmosis systems seem to take a really long time to fill tanks, especially how often I change the water, does anyone have one that is faster? I have a drinking water R/O installed, but to get 5 gallons worth takes so long and it runs out of juice. To fill my tanks I have setup from the shower that I use my python to fill and can adjust the temp, but the water is definitely hard based on my preliminary results.

2)Has anyone had any luck with API water softener pillow? I have read mixed results and would like some input before I start experimenting.

3)Water Softeners: general internet consensus from what I have read is potassium is the way to go. Would this be worth the investment to soften the water or just mask an underlying problem? Any Ill effects for the fish?

Thank you for any input, advice, and for any recommendations.

PS: Driftwood is being soaked as I type, not sure how much of a difference it will make.

I just switched to prime 2 weeks ago for water conditioner based on my LFS recommendations.







150 gallon
Fluval FX6
2 Oscars
1 Jack Dempsey
1 Black Convict

75 G ... TBD?
Fluval 406
1 Albino Bristlenose
1 black pleco (unknown what type, fully aware I may have to rehome in the future if he is the large type)
Cycled and ready for some fish, would like to do freshwater, i love cardinal tetras, Angels, schooling fish, need help with getting my hard water straightened out!

 

[Caliban07]

RO would be the best way to go. You can invest in your own system but I really don't see the problem. Your fish are healthy? That is the best possible outcome in this hobby. Don't change anything and keep doing what you are doing [emoji106]

 

[flchamp89]

Thats what I was going to say...im 7.4 with same gh/kh

 

[wetfarticus]

Im new and don't know much, so take this with a grain of salt. I have extremely hard water out of the tap. I got a RO system and like you it takes all day to fill a tank and I can't adjust the temp so it is very cold.
I didn't want to spend ungodly amounts of money on a sump tank and pump, etc...
my solution was to buy a 30 gallon poly barrel, with wheels so I could keep it out of sight. I put a float valve on it so all I had to do was hook up the RO to it and walk away.
Installed a 3/4 inch bulkhead at the bottom with a ball valve and coupling system. Got a 6 ft length of 3/4 tubing that is the same size as used on my canister filter. Put ball valves and couplers on both ends.
Then I put a tee fitting on my intake tube on my filter with 2 ball valves and a coupler on one side.
Sounds complicated but its actually quite simple.
I have 30 gal room temp RO water on demand. All I need to do for water changes is wheel it to the tank, connect the tube from the barrel to the tee fitting, close the valve at the tee coming from the tank, open the valves at the tee where your tube attaches with the couplers, open also the valves on the tube and at the bulkhead on the barrel. I turn my pump back on and my filter draws the water from the barrel rather than from the tank. Its amazingly simple. Takes no time at all to fill the tank and the water gets filtered again before entering.

That was long winded and probably hard to understand or it seems complicated and difficult. Its not, I assure you.

 

[J.Mcpeak]

RO will pretty much equally divide your tank water, which could leave you with a dangerously low Kh.

It will make a difference to soft water fish, they look better and live longer. I've had it both ways water wise so can vouch for each. The effect is immediate. The clarity of the water also improves.

Going with tetra, you'd want GH around 6, that's simple enough, add approx 66% RO to tap! that would divide your 18gh to pretty much 6, but the same division would happen with Kh. Not good if it's only 7! You'd be down to 2 or 3 Kh. At 3 Kh things get a bit dicey, especially if the tank is medium to heavy planted.

Test tap Kh, if it's much higher than 7, you're getting Kh depletion in tank. Kh is used up (it is temporary hardness after all)
GH is also used but much less so by comparison.

Water changes achieve more than nitrate removal and that shouldn't be your sole reason for doing one. (That's a good tip from someone who has made that mistake.)

Driftwood doesn't soften water. The tannins (which turn the water brown) are responsible. The effect is negligible in my experience, not worth counting on.

RO units are rated at Gal per day. If you want faster output, get a bigger model.
75gpd in warm weather makes about 200 litres in 24hrs. It is temperature dependent, I live in uk so if it's warmer it'll be faster. Optimal condition are 24'c at 65psi. Where it would produce the full 75 gal not 52 (200litre).
Gals, U.S. liquid.

 

[mikesurt]

What do you use to top up the daily loss of water due to evaporation.

 

[J.Mcpeak]

Usually I factor it in at water change time.
Eg.
Tank should be 120tds
Evaporates to give a reading prior to water change of 140tds
Top up with 100tds.

But this is dependant on volume changed.
(2 buckets on 100-120litres)

That gives a safety envelope, when first using RO I was chasing TDS numbers and topping up with RO to achieve that. Then I had a decrease of GH/Kh despite the TDS being the same.
So now I've adopted this method, which I've been using for maybe 10 years give or take.

The big tank will take a 25 litre container of RO each water change depending on temperature and humidity. Less humid and hotter takes this amount roughly, less winter time.

The puffer usually gets RO depending on SG.