water chemistry


Junior Poster
Nov 12, 2008
Hi All,

This is my first post on this site. I look forward to learning from y'all! I've had a reef for the last 8 years and had a planted tank 25 years ago.

Got sick of making salt water and converted my 180 reef to a planted tank about 3 months ago. All is growing great but have pH/dKH questions.

Have 3/4 ADA Amazonia II, 1/4 sand in the open areas, CO2 injection into my circ pump inlet, 180 tank, and another 90 gallons of filter/sump/water change system, (270 total) 200W T5-HO 6500K. 100 W from 2-11 PM and 200 W from 6-10PM. Lots of plants, wood, ricca and quite a few (too many) fish. tetras, angels, corys, rasboras, fancy guppies. All appear to be very healthy.

My make-up water is 7.7 pH and about 2.9-3 dKH measured with hach/salifert. I change about 40-50 gallons 2-3 times per week making my water 16 days old as of now. I've been adding about 100 ml Vinegar to the water changes which lowers the pH to 7.4. Temp control runs between 75 and 76 degf. I have a RO/DI system if necessary. I fertilize with 35 ml of homemade Brightly "k" daily and add 50 ml of PPS-Pro with water changes. Only have hair algea.

The tank (measured at various times of day) seems to stay pretty much at 7.4 pH and 2.8-3 dKH.

What is the best way to lower the pH and increase my dKH?

Should I even worry about it?

Any other comments?




Lifetime Charter Member
Lifetime Member
Jan 24, 2005
Sacramento, CA
Adding vinegar to the water is not a good idea. So, I would discontinue that practice. The best thing to do is to leave the KH and pH to be whatever they are. Neither is really important, other than that very high KH isn't a good idea for the fish. Also, your tap water or change water will have CO2 dissolved in it to be in equilibrium with the atmosphere. And, with any CO2 in the water, the pH will go up when the KH goes up.

I don't understand why you do so many water changes. Most of us do weekly big water changes, around 50% or so, some do them less often, and others, like me, do much smaller changes much more often - I change about 5 gallons a day of a 45 gallon tank, by constantly tricklng filtered tap water into the tank, with the excess going out an overflow.

If you read http://www.barrreport.com/estimative-index/62-estimative-index-dosing-no-need-test-kits.html you will understand what most of us are doing with water changes and fertilizing. It is a method that is proven to work for many different setups. But, your tank is a relatively low light tank, so you don't really need much fertilizing, so this, http://www.barrreport.com/estimative-index/2817-non-co2-methods.html, may be a better plan for you to follow.


Junior Poster
Nov 12, 2008
Hi Vaughn,

Thanks for the feedback. Not worrying about the pH or dKH would make life a lot easier. Those links make interesting reading. So the plants and fish really do adapt to different conditions? Is it mostly when breeding that the water conditions should be perfect?

Having grown up in the tropical rain forest, and seeing the frequent floods, tropical fish and plants must be much more adaptable than the fish books would leave you to believe.

Looked at the effeciency of the GE 54W T5-HO @ 6500K and after a few weeks of running my four bulbs are roughly equivalent to 2x150W Metal Halide with a whole lot better dispersion. So the amount of light is not that low. Nothing compared to the 1600W I had on the same tank when it was a reef. My goal is minimize maintenance time but to get decent growth and keep all of the creatures happy. So I try to automate as much as possible. Still had the CO2 from the reef or I probably wouldn't have bothered.

Without the water changes, the water quickly turns brown, and being extremely busy with my 2 year old, work, exercise and other hobbies, big water changes take me too much time and also disrupt my filtration system. The 40-50 gallon water changes take me no time at all:

1) isolate the filling tank by closing 3 valves
2) open drain valve
3) come back 10 minutes later, add chemicals, start filling tank circ pump and heater and open automatic filling system valve
4) let the tank fill and water stabilize for a few hours and then open the isolation valves

unfortunately in a 270 gallon system, that is only a 17% water change so I do it somewhat often.

The only thing that takes real time on the tank at this point is reading, cleaning the overflow stainers from plant material and ricca, and getting rid of hair algea. It is the only algea I have, any tips on creatures that eat it? My angels and gouramies seem to like it.



Tom Barr

Staff member
Jan 23, 2005
Automation of the water change is the best bet for folks that want good parameters for the fish.

There's no better choice I know of. Some will claim test the water etc, but for fish health, there's no simpler better method that can be automated, testing NO3 cannot be automated, nor PO4, nor K+, nor Fe, and these need calibrated each time you do a new batch.

You can set up the system to do semi automated water changes("WC's" from here on). Simply have the drain and fill on manual ball valves, but hard plmbed.

For a 270 gal tank, go 1-1.5" PVC.
For the fill, anything from 1/2" 3/4" with hot and cold, run a large carbon prefilter(change every 2-3 months), to remove any Chlorine etc.

With the manual override, you can easily change out 50-70% of the tank in about 1 hour. The drain will allow you the time to scrub the glass, clean any sponges, prefilters.

The refill will allow the time to trim and scape.
So in about 1 hour, you can do most things you need to do.

I have been doing this for years on a larger tank than this, and have some tanks set up this way with 1600 gallons.
So I know it works well.

Full automation is nice as well to do daily changes.

If you can do 15-20%, that' great also.
You'll also feed the plants and fish daily as well.

Takes 10-20 seconds to feed plants and about the same depending on the food for the fish.

Light seems fine.
Main thing for you will be the CO2.

You can reduce the light down a bit later after things fill in a bit, and also chose plnts that require much less work for the design and scape you like. That will take some time, but you'll see what we mean. Many aquatic plants are weeds and need hacked back often. New scapers often go on and on about trimming and how much they love some weedy new stem plants, we hear this less and less frequently as they have to hack it for several years:eek:

So light, plant choices are the best solutions there. Automated or semi automated for the water changes, and quick easy dry dosing.

You only dose 3-4 thigns and that's it, it quickly becomes an old simple routine rather fast. The hardest thing, much like a reef and Ca++/KH, is the CO2.
And it's even more important to keep a good eye on than the Ca/KH for a reef.

We can reduce the demand for CO2 by reducing the light, this makes things more resilient and stable so if you miss a target, forget to dose, whatever, you are erroring on the safe side.

WC's, dosing non limiting levels, low light, good plant choices, routine filter maintenance, are all things that will help fish and plants.

Tom Barr