High nitrate with ph crash

[Ganz]

Hello all. I have a planted 20 gal community tank with a gravel bottom,HOB filter, wood and an assortment of fishes. Rams, orange flash cacs, rainbows, odessas. This tank has been set up for a year. I use only RO water tds =0 ph = 6.5, and up until now everyone has been happy. A few days ago I lost a horsehead loach now an Odessa is dieing and the other Odessas don' t act normal.
I generally don't obsess on the water of this tank, but I got an accurate Ph reading of 4.3, then I see that the nitrate is about 80. I have no idea what the cause is. Did a 25% water change, dropped an air stone in the tank last night (thinking C02 problem),put some sea shells in this morning ( thinking that I need a buffer). I do believe that the Ph is killing the non-cichlids. I add no chemicals to any of my tanks.
Any thoughts or advice would be helpful.

 

[Kruz]

I don't when last time you tested your tank? It could be a number of thing. It could of been your Co2. It happens to crash the PH time to time. They do make a PH controller for your Co2. It's not a must at all just check if 3 of 4 times a week. I don't know how long your fish were dead in the tank for or the last time you did a water change, but that could have contribute 80 ppm of nitrate's. Sometimes I feed heavier when breeding and it raiser my water parameters. It could be a number of thing that are contributing to the add up to this ect.
I would do more testing after your water change, a few hours later. Test not just for PH and Nitrates, also test for ammonia and nitrites at least. you can test for more but though are the tall tail signs of how your tanks doing. the shells where a good idea to make your PH raise. Just don't raise it to fast or the same thing could happen. Hopefully that's helpful Ganz good luck man.

 

[regani]

High nitrates are a sign of build-up of waste either due to overfeeding, large amount of organic matter decomposing in the tank (e.g.dead fish, decaying plants), insufficient water changes, or a combination of (all of) the above. To bring the nitrates down do a couple of larger water changes and then have a regular schedule of weekly water changes of about 25% to keep them down. Also have a critical look at how much you feed and maybe reduce the amount.
To address the low pH, you will need to add some buffering capacity to your tank. With pure RO water your tank will have no carbonate hardness (KH) and nothing will prevent the pH from dropping down, especially if you are using CO2 as well. Quite a few biological processes, including photosynthesis, use up some carbonate as well, so no carbonate will increase the risk of the pH dropping uncontrollably. To get at least a little bit of KH you can mix in some tap water (depending on what the KH of your tap water is), add small amounts of bicarbonate, or add some shell grit, aragonite or similar to your tank or filter. With the latter make sure you can easily remove excess as you may have to experiment a little to find the right amount that doesn't drive your pH up too much.
Some organic compounds such as humid acid, tannins etc. have some buffering capacity as well but they are not write as effective and buffer at a lower pH so are not so easy to rely on as sole source for your buffering.

 

[gerald]

Agree with regani -- decaying organic matter and nitrification of ammonia (into nitrate) are acid-producing reactions, and you have no buffering to neutralize it. (NH4 --> NO2 --> NO3: those H's released are the acid). I would put a little aragonite (crushed coral) in a box filter - just a tablespoon or 2 - to slowly dissolve and neutralize acid as it is generated. Regarding the nitrate build-up, that happens if the total nitrogen added via fishfood exceeds what your plants can use. Fast-growing floaters like limnobium, salvinia, certopteris, etc are great for sucking out nitrate (and ammonia) in tanks with a high fish load. Just keeping thinning it out each time it covers the surface and you're removing lots of excess nitrogen with it. Do the water changes too of course, but fast-growing plants will give you a margin of safety if you fall behind on water changes. I dont know what plants you have, but slow-growers like anubias, crypts, java fern, etc probably cant use all that N fast enough with barbs and rainbowfish (pigs) in the tank.

 

[Kruz]

Agree with regani -- decaying organic matter and nitrification of ammonia (into nitrate) are acid-producing reactions, and you have no buffering to neutralize it. (NH4 --> NO2 --> NO3: those H's released are the acid). I would put a little aragonite (crushed coral) in a box filter - just a tablespoon or 2 - to slowly dissolve and neutralize acid as it is generated. Regarding the nitrate build-up, that happens if the total nitrogen added via fishfood exceeds what your plants can use. Fast-growing floaters like limnobium, salvinia, certopteris, etc are great for sucking out nitrate (and ammonia) in tanks with a high fish load. Just keeping thinning it out each time it covers the surface and you're removing lots of excess nitrogen with it. Do the water changes too of course, but fast-growing plants will give you a margin of safety if you fall behind on water changes. I dont know what plants you have, but slow-growers like anubias, crypts, java fern, etc probably cant use all that N fast enough with barbs and rainbowfish (pigs) in the tank.

Ya crushed coral help a lot with Co2 and RO water dropping your PH/KH, tap water in almost a must to help your RO. You don't need a lot of it ether you'll find the right mix, test and see. All of our tap water is different. Just make sure if the crushed coral in your filter box/canister is rinse out from time to time. It can also buildup Nitrates. If you want to keep the
beneficial nitrifying bacteria in your tank then just rinse it out with the water from your tank. I use the water from my water changes. The biological process that converts ammonia intonitrite then into nitrate. To make it easy for you, some times people don't know what NH4 converts into NO2 then NO3. It just makes it easy for people who are having tank problems can make it as easy us you can for them. I have worked in a few different Fish/Reef store (and not Petco or Petsmart) on the west coast for a few years and the easier it is for them the more your average joe will stay in the hobby. Ganz more info on your tank would help us out more like the plants and how they are doing like gerald said . How often you do water changes. Its all good the info you did provided us with was a lot more then most people give on forms . hopefully you can give us an update on your tank so we can get into to this more good luck bro.

 

[Hague1982]

I'd just use a bit of sodium bicarbonate to raise your KH a little if it needs it.

 

[dw1305]

Hi all,
I think the real problem is that the OP is trying to keep fish from hard and soft waters together, and I'd suggest re-homing the Barbs and Rainbows to a tank with much harder water. I also think he needs some plants, they honestly are the single biggest factor in

To address the low pH, you will need to add some buffering capacity to your tank. With pure RO water your tank will have no carbonate hardness (KH) and nothing will prevent the pH from dropping down, especially if you are using CO2 as well. Quite a few biological processes, including photosynthesis, use up some carbonate as well, so no carbonate will increase the risk of the pH dropping uncontrollably. To get at least a little bit of KH you can mix in some tap water (depending on what the KH of your tap water is), add small amounts of bicarbonate, or add some shell grit, aragonite or similar to your tank or filter. With the latter make sure you can easily remove excess as you may have to experiment a little to find the right amount that doesn't drive your pH up too much.

I would put a little aragonite (crushed coral) in a box filter - just a tablespoon or 2 - to slowly dissolve and neutralize acid as it is generated. Regarding the nitrate build-up, that happens if the total nitrogen added via fishfood exceeds what your plants can use. Fast-growing floaters like limnobium, salvinia, certopteris, etc are great for sucking out nitrate (and ammonia) in tanks with a high fish load. Just keeping thinning it out each time it covers the surface and you're removing lots of excess nitrogen with it. Do the water changes too of course, but fast-growing plants will give you a margin of safety if you fall behind on water changes.

I'd apply the same method as "Gerald" and "Regani" suggest.

I would prefer the biological aragonite form of calcium carbonate (CaCO3), "Oyster Shell Chick Grit" is a good cheap source. I wouldn't use sodium bicarbonate as it will all go into solution and not add any carbonate buffering.

cheers Darrel

 

[Hague1982]

.

I would prefer the biological aragonite form of calcium carbonate (CaCO3), "Oyster Shell Chick Grit" is a good cheap source. I wouldn't use sodium bicarbonate as it will all go into solution and not add any carbonate buffering.

cheers Darrel

Just so I understand a little better. Would continuely adding sodium bicarbonate at each water change to aquire the same Kh level not have the same effect as using oyster shells though?

 

[gerald]

Yes I think so. Whether you add alkalinity as carbonate CO3 (aragonite, coral, shells, limestone) or as bicarbonate HCO3 (baking soda), once it has dissolved the relative amounts of CO3 and HCO3 will be determined by pH: they shift back and forth in an equilibrium reaction. Darrel and I both like the coral/aragonite carbonate method because it dissolves slowly in response to acid production, so it doesn't push the pH up too far or fast (like baking soda does) when you're keeping soft/acid fish.

 

[Mike Wise]

Won't sodium bicarbonate increase the electrical conductivity higher than the same amount of aragonite (calcium carbonate)?

 

[Hague1982]

Yes I think so. Whether you add alkalinity as carbonate CO3 (aragonite, coral, shells, limestone) or as bicarbonate HCO3 (baking soda), once it has dissolved the relative amounts of CO3 and HCO3 will be determined by pH: they shift back and forth in an equilibrium reaction. Darrel and I both like the coral/aragonite carbonate method because it dissolves slowly in response to acid production, so it doesn't push the pH up too far or fast (like baking soda does) when you're keeping soft/acid fish.

I never though about it dissolving slower in acidic conditions. Cheers.

 

[regani]

I never though about it dissolving slower in acidic conditions. Cheers.

I think you misread the earlier post, it said that the aragonite dissolves 'slowly under acidic conditions'; it won't dissolve much under neutral conditions and actually dissolves faster when more acid is present.

Won't sodium bicarbonate increase the electrical conductivity higher than the same amount of aragonite (calcium carbonate)?

yes, generally it will. if you add a teaspoon full of each into neutral water the bicarb will all dissolve and raise the KH and conductivity; the aragonite will very slowly dissolve until the maximum concentration of CaCO3 in the water is reached (which is much lower than that of sodium bicarbonate) giving a lower KH and conductivity compared to the bicarb butt also raising GH.
however, this changes somewhat when acid is present. the acid will react with either the bicarb or the dissolved carbonate from the aragonite generating CO2 leading to a drop in KH but also 'pulling' more of the aragonite into solution (a question of chemical equlibrium), hence dropping KH but further increasing GH in case of the aragonite.
if there is a lot of acid present (or is generated over time) this will continue until either all acid or all bicarb or aragonite is used up. if that happens the resulting final conductivity would be roughly the same in both cases.

the main difference between bicarb and things like aragonite is that with bicarb the whole buffering capacity is already in the water column, affecting KH, pH, and conductivity; with aragonite the buffering capacity is 'hidden' and only gets activated 'on demand', so the initial effect on KH, pH, and conductivity is lower, but there will be an increased GH.
bicarb reacts fast with any acid that is there, but aragonite will take time to neutralize larger amounts of acid that are generated or introduced into the tank; so pH swings are still a possibility with aragonite under some circumstances.

 

[Ganz]

Thanks for all your thoughts and input on this. It seems that my tank has heart burn.

I may have confused things a bit in my initial post. This is a low tech tank. No C02 injection, plants are just amazon swords, java fern, sagitaria, and water sprite ( sold as wisteria around here).

I added 3
palm size river stones (I believe they are Sandstone) to the tank. I
had positively identified these stones as the buffering problem when setting up another tank (i wanted the Ph down). I acid tested them and they fizzed like Alka seltzer. The stones and shells seem to have stopped the Ph free fall. I thought about using baking soda but I had no idea of the amount to use.

So here is where I am 48 hrs later, 2 water changes 25%, calcium carbonate added (unknown proportion), vigorous aeration, a real good cleaning, oh yeh I pulled out a lot of Java moss that was trapping debris.

Gh up to 50-60, Kh up to 20, No2 = 0?
No3 down to 40, Ph =5.8

Nitrates coming down rapidly and ph rising slowly. But the Gh has tripled?
And the Kh did nothing. Does this mean that the water still has no buffer?

I didn't lose any more fish. They seem to be recovering ok. Even an Odessa that was actually upside on his side is recovering.

I knew that I would here from someone about this mix of fish. This is my son's tank. I keep Apistos in a 55g. The odd thing is that up until this ph/nitrate issue, this mix of fish seemed to be thriving as a community. Beautiful coloration and finns. The information on Odessa's habitat is sketchy. I've read hard water, fast moving, then I read still, slightly acidic water. Then i read that they are nolonger found in the wild at all! They don't seem like a barb! The temp in this tank stays around 82c. That's not barb weather either, but besides this mishap, they have been flashy, strong and healthy.

 

[regani]

the sandstone will buffer away the acid over time. it just dissolves very very slowly so all KH that is generated by dissolving is immediately 'eaten up' by the acid present and the calcium carbonate that is part of the sandstone will raise the GH (see my previous post). give it some time and the tank will find its equilibrium.

some good info about the odessa barbs can be found here http://www.seriouslyfish.com/species/pethia-padamya/

I love odessa barbs, they are some of the prettiest barbs around, imo. I should think about setting up a tank for them, maybe. hmmm .....

 

[Ganz]

Regani I have been reluctant to add tap to the tanks after fighting my hard water, before I went to RO. But, I'll try a topper this evening. The shells that I added are actually on a string so they can be easily removed from the tank. Thanks to all the post here, I think that I am finally getting to understand carbonate buffering. I had wondered how long a tank could float along with no buffer.I think that I may have tipped the scale in this tank when I started giving the fish a little extra brine shrimp. Although I never saw any food hit the bottom, i am sure that it changed the amount of waste/chemistry in the tank. Probably just enough to throw me over the edge.

 

[gerald]

regani thanks for clarifying that aragonite dissolves faster at low pH than at high pH - that's exactly what I meant - sorry Hague, my wording was confusing. You can think of aragonite as a sort of "invisible buffering". It's in solid form so it wont show up as measured alkalinty in a KH test, but it dissolves (slowly) as acids are produced by nitrification, organic decay, and other bio-chemical processes.

regani mentioned "pH swings are still a possibility with aragonite under some circumstances." YES and here's my story: I had six Tanganyikan Synodontis lucipinnis (i think) in a small tank with dense plants and aragonite gravel in a box filter. Two months ago they weren't eating well, then I found two dead a week or so later, and discovered the pH was a little below 5. I had not cleaned the filter in several months, the aragonite had gotten coated with slime and was no longer able to buffer the acid. After a water change and filter cleaning (stirring the aragonite to re-expose the mineral surfaces) the survivors recovered and were eating and acting normal within a week, like your barbs. I was amazed that a Tanganyikan fish could survive pH 5 exposure, probably for 2 or 3 weeks before I found the problem. I guess the lake-dwelling Synodontis still have some remnant acid-tolerance from their river-dwelling ancestors.