# Low KH, pH and high GH



## GimmeGills (Sep 29, 2010)

Long story short - I started to set up a low tech, low light 10 gallon tank about a year ago, got it started then had a bad shipment of plants, got frustrated and ignored it for 10 months. I finally got tired of having an algae infested tank sitting in the room so I scrapped away the algae, got re-inspired and decided to go through with my original plan. 

I did 2 25% water changes over the course of 2 weeks and tested the water. I was a bit surprised to find a pH of 6.2, a KH of 40 and and a GH of 300. Out of the tap my water is a pH of 6.6, a KH of 80 and and GH of 100. What could possibly be causing such a reduction in pH and KH and a rise in GH?? Is the 

Specs:
Flourite substrate
2 pieces of slate for decor
A large piece of driftwood
1 Anubias barteri
1 Echinodorus sp.
Marine Eclipse hood/filter system
No ferts as of yet, not nearly enough plants yet!

Just yesterday added 5 neon tetras and 2 cory cats. The filter system disturbs the surface pretty well so I don't think CO2 is driving these results... Any suggestions? Should I just continue weekly water changes to try and bring it up or should I consider adding supplements?


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## davemonkey (Mar 29, 2008)

The driftwood and the "slate" could both be contributing to water chemistry changes. Driftwood can leach acids and the slate could be breaking down, depending on what material it is (sandstone, limestone, etc... ) releasing minerals in the water.

I would be more concerned right now about getting more plants in the tank than anything else. Your pH is fine for a planted tank.


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## Diana K (Dec 20, 2007)

You are dealing with a tank with Old Tank Syndrome. 
The next post is an article I wrote about OTS in a non-planted tank. 
In a planted tank the plants (algae is a plant in this respect) create some slightly different changes than are detailed here, but the idea is the same.
If you do not have any fish, then there is no problem with doing a big water change to set things right. Most plants are not going to care that the water parameters change so fast. But with fish, shrimp, snails and so on, go slow. 

Topping off with tap water has contributed to this, too. 
As water evaporates it leaves behind the minerals. When you top off, you are adding more minerals. The plants (Algae) use some, the bacteria and other microorganisms use some, but generally topping off has been adding more calcium and magnesium than is getting used up. 
On the other hand, the tap water contains so little KH that the plants and other life has been using it up just a little faster than you are adding it with topping off.
Anyway... on the the article:


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## Diana K (Dec 20, 2007)

OLD TANK SYNDROME
Aquariums with less than optimum water changes will accumulate toxins that can poison the fish, shrimp, snails and plants. As nitrate climbs and the decomposing bacteria use up the minerals in the tank the pH can drop, to 6.0 and lower. Nitrospiros bacteria (the actual nitrifying bacteria) do not do well at lower pH and may be dead. Ammonia climbs, pH drops, nitrate may be very high. The GH may be quite high if the tank has just been topped off using tap water. 
The fish might have adapted to the high nitrate. Those that could not adapt have died. If you try adding new fish, they die. The low pH is keeping the ammonia in the NH4+ form, which is less toxic Any water changes create changes in the GH, KH and pH levels and the fish become sick or die. 

This tank is suffering from Old Tank Syndrome. The best, safest cure is a long, slow change back to optimum conditions. The fish have been living like this long enough to adapt to the low GH, KH and pH as well as the high nitrate. An instant change back to 'perfect' would be too much for them. 

Here is what I would do: (and why) 

FIRST WEEK: 

1) 10% daily or even twice daily water changes. Use a dechlorinator that locks up ammonia, nitrite and nitrate. Prime, Amquel Plus... (Any larger water change creates too big a water chemistry change) 

2) Zeolite in the filters. Get 3 bags: every day swap out one bag and rejuvenate it overnight in salty water, then soak in fresh water (RO or Distilled is best) You will always have 2 bags in the tank, and one in rejuvenation. (Zeolite removes ammonia, but gets filled up. It is cheapest to buy a large jar of it and cut up some nylon stockings as bags.) 

3) If there is over 1.5 watts of light add all the plants you can. Fast growing stuff like Anacharis is best. (Plants are the fastest ammonia removers. But under 1.5 watts they are more likely to rot than to help. If fish eat them, not to worry, just feed the fish less. Plants are low nitrogen compared to high protein fish food, thus contributing less ammonia waste to the problem) 

4) Deep and thorough gravel vac as much as you can this week. (Decomposing gunk is lowering the pH and contributing to ammonia problem) 10% water change does not allow for much gravel vacuuming in any one session, but you can get over the whole tank bottom at least once this week. 

5) Order Nitrospiros species of nitrifying bacteria. Microbe Lift’s Nite Out II, Tetra Safe Start and Dr. Tim’s One and Only are good. Do not waste your money on any other source of ‘bacteria in a bottle’. Wrong ingredients. Other sources of ntrifying bacteria include other healthy, cycled tanks. You could add some floss or sponge filter media from a healthy tank to this ailing tank, but the bacteria will not grow very well in such low pH. I would not add it this week. Do not take so much filter media from the established, healthy tank that it gets into trouble. These bacteria will not do very well when the pH is too low, but as soon as the pH has climbed to 6.5, add whatever source of bacteria you can to boost the population in the tank. 

6) Feed less. Half what was fed before. Feed low protein foods if the fish can handle them. (This is the Garbage In = Garbage Out principle. Less GI = less GO.) 

7) Clean the filter in water removed from the tank. Tap water with chloramines or chlorine can kill whatever nitrifying bacteria may be alive. 

By the end of the first week the ammonia will be significantly lower, the pH slightly higher, nitrite might be showing and nitrate might still be very high. Gravel is much cleaner. O2 levels are rising, benefiting fish and nitrifying bacteria. If the tests show nitrite, add sodium chloride (salt) @ 1 teaspoon per 20 gallons of water. Add this much whenever you do a water change based on the amount of the water change. If you do a 5 gallon water change add .25 teaspoon to the new water. Keep this up until the nitrite level consistently reads 0 ppm. 

SECOND WEEK 

1) Do daily 20% water changes, and deep gravel vacs. Also, clean the filter. (The larger water changes are going to be altering the pH a bit more, but are removing a lot more nitrate. As the nitrifying bacteria get going again removing nitrate is very important.) 

2) Add nitrifying bacteria. If you use a bottled product then no more gravel vacs the rest of the week, and no water changes for a couple of days. Do not clean any filter for a week. (Allow the bacteria to settle in the filters and gravel without removing it or knocking it off the gravel or filter media.) If you were able to get cycled media from a healthy tank then keep up the water changes and gravel vacs. 

3) Continue swapping out the zeolite bags, but if the ammonia tests show that the ammonia is a lot lower, just swap out one bag every other day. (The nitrifying bacteria need ammonia to eat. By removing it with zeolite you are starving the bacteria. It takes several days for the bacteria to settle in and really get going on the ammonia, though, so keep the zeolite going this week. Might still need daily replacement) 

4) Continue feeding the fish significantly less food. If they will eat vegetables or plants this is better. 

After the second week I will expect the ammonia to be gone or almost gone. The nitrifying bacteria might be having a hard time. Be patient. It will get going soon. The pH may not be the same as the tap water yet, but it is OK if it is a little higher with the ammonia getting so low. Continue using a water conditioner that locks up ammonia, nitrite and nitrate so the fish are protected. 

WEEK THREE 

1) Clean the filter. Be very gentle, the nitrifying bacteria population is still establishing itself. 

2) Continue with daily water changes, but if the pH, GH and KH are closer to the tap water then increase them to 25%. 

3) Resume deep gravel vacs (if you had stopped because of adding bottled bacteria). 

4) Decrease the use of zeolite. Monitor the ammonia. If the plants and bacteria are handling the ammonia, then stop using zeolite. If the plants and bacteria are not up to it yet, keep using the zeolite, but perhaps only swap out the bags a couple of times this week. (The zeolite can only be rejuvenated just so many times, then is too plugged up with stuff that cannot be removed. Monitor the ammonia, and change out the zeolite bags, but remember there are other things removing the ammonia, too. It might be that the zeolite is dead, and it is time to throw it away)

By the end of week three the aquarium is likely getting back into shape. pH is much closer to the tap water pH (and KH and GH are matching the tap, too). Nitrifying bacteria and plants ought to be handling all or almost all the ammonia. You might be seeing nitrite. If nitrite shows then add 1 teaspoon of salt per 20 gallons of water. Nitrate may still be too high, (though a lot lower than 3 weeks ago). The nitrifying bacteria will be creating more nitrate as they establish themselves. Plants will be very helpful here by removing ammonia before it even gets to the bacteria.

FOURTH WEEK: 

If the pH, KH and GH of tap and tank match then do as large a gravel vac and water changes as needed to really get the nitrates down. 
Goal: Ammonia and Nitrite will ultimately read 0 ppm, but if the tank is still cycling try to keep the ammonia < .25 ppm, and the nitrite under 1 ppm. 
Try to get and keep the nitrate under 20 ppm. Lower is better. 

If the tap water pH, GH and KH are not close enough to the tank to permit larger water changes then do more frequent ones, perhaps 30% daily. It is also a good idea to keep up the deep gravel vacs to continue removing debris. 

Eliminate zeolite. (Now that the bacteria is getting back to where it should be you do not need this emergency removal product, the bacteria are doing the work.)

Offer the fish a little more food if they really need it, but people who allow a tank to reach this condition are often over feeding anyway. Perhaps the new diet really is better. If your fish do need a higher protein diet, more bugs, worms, shrimp and other meaty foods add these back slowly and monitor the ammonia, nitrite and nitrate levels. 

ONGOING MAINTENANCE:

Set up a schedule of weekly water changes. This might be 25% once or twice a week. If the tap water and the tank water have similar water chemistry then you can do larger water changes. Clean the filter regularly. Vacuum the floor of the tank. 
Feed the fish a varied diet, making sure they eat all the food. Fast them one day per week. 
Test the water weekly. Optimum readings are:
Ammonia 0 ppm. Any other result is an emergency. 
Nitrite 0 ppm. Any other result is an emergency. 
Nitrate < 20 ppm. If it gets higher than this you will need to do more frequent or larger water changes. 
GH, KH and pH ought to be stable, not changing from week to week. 
Top off with Distilled or Reverse Osmosis water.


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## GimmeGills (Sep 29, 2010)

Diana, this was EXTREMELY helpful! Thank you so much for taking the time to reply and share this article. I was very confused and this seems to sum up my problem and give me a great solution. I'll get started on the daily regime and hopefully things back into more normal parameters soon! I do appreciate the advice.


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## maxthedog123 (Jun 25, 2007)

Sorry to repost on an old thread, but this is very relevant to me. I was testing water yesterday and ran the API test for pH. I don't typically test for that, but I was puzzled that the pH showed up as 6.4.

This is my 55g tank that has been set up for probably 3 years.

Current stocking: 4 angels (~2in each), 5 denisonii barbs (~1.5in each), 2 columbian tetras, 4 scissortail tetras (m. intermedia NOT rasbora), 1 SAE and 1 BN pleco. Lots of plants in this tank: vals, java fern, banana plant, wisteria, 1 large sword, 2 small swords.

As a side note, I believe my tap water is around 7.2.

To be honest, my maintenance has been a bit suspect lately. (I know, but sometimes life gets in the way.) I've been changing the water about once every 2 months. I know there will be disagreement on that, but I have been going lower and lower tech for some time now. I have 2 aquariums that are pure Walstad setups. My 55g and 30g now have low light, tons of plants, no CO2 and light fertilizer maybe 1x per week. (Read Tom Barr's sticky on his site about water changes causing fluctuation in CO2 levels. For a lower tech setup, there is much to read on changing CO2 being a bad thing for algae control.)

My nitrates seem stuck at about 40. After a water change today, the results were as follows: pH 6.6, ammonia 0, nitrite 0, nitrate 40. I tested GH and KH for the first time in a long time. KH was either 1 or 2 - it was hard to read, but no higher than 2. GH was around 20. Just for fun, I tested the tap water: KH was 4 and GH was around 20. (Lots of limestone here in Southwest Ohio.)

I also cleaned the Fluval 405 which hadn't been cleaned in about 6 months, so that may make a difference too. I have a 305 on the tank as well - I need clean that. Is it better to wait to clean it or is it more imperative to get the dissolved organic gunk/sludge out of the system?

The plants grow well - my Vals are at the top of the tank and my sword puts out new leaves on a very regular basis. Wisteria is booming. The only thing that doesn't seem to get very large are the crypts, but they may just be getting muscled out for the nutrients.

Just for a complete picture, I switched from T5HO lights (108w) to T5NO (~56w) several months ago. I quit running CO2 at least a year ago. (Dialing down the lights got the BBA in check.) I use the Seachem liquids around 1x per week. Will be moving to dry ferts when the 2g jugs of that I have are gone.

I don't think based on the current size of the fish that I am particularly heavy on fish load. Everyone has been fairly healthy except for 1 angel who developed pop eye and started to have some erosion on one of it's gills. I treated the tank with Marycn2 (sorry, QT is not up and running). I had to put the angel down. I've given everyone else a very close inspection over the last 2 weeks and I have not seen any other signs of health issues.

So, I will test later to see if pH move at all. Do I need to do something to buffer the water? 

I am going to self diagnose and then ask for your thoughts. I am going with the cause of low pH due to excess nitrate buildup in the canister filters. (Somewhat of an "old tank syndrome".) From what I have read, breaking down nitrates and/or excessive decomposing organic material will cause a drop in pH as well as a potential drop in KH due to acids being produced.

Opinions? Just more slow maintenance (to avoid a crash or just plain killing the fish through shock) or do I also need to consider a KH buffer? It seems like my KH is rather low and I could benefit from buffering. What is the best method to buffer KH? Old fashioned baking soda? A specialized buffering product? Other remedies?


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