Water parameters - Tropical Fish Keeping - Aquarium fish care and resources
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post #1 of 5 Old 07-18-2011, 07:52 PM Thread Starter
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Smile Water parameters

I have a 40 gallon freshwater tank with fake plants (and shaded areas of the tank for fish to hide in) along with lots of places for my clown loaches to hide in. I currently have 5 clown loaches (all doing well for many years (my oldest I have had for 9 years and my youngest I have had for 1 year)), 1 red eye tetra, 1 neon tetra, and 3 golden pristella tetras. I do weekly water changes of ~10-20% and a bigger 50% water change once a month when I clean the tank and the Fluval 305 filter system. I have never had a problem with my clown loaches (1 of them I have had for 9 years). Over the past 6 months, I have lost 5 of the neons and 2 of the red eyes. I did not see any visible signs of infection or problems. My tank parameters have remained relatively steady (I check once a week before I do the water changes and the cleanings).

I just checked my tank:

Temp = 80 F
pH = 6.5
GH = 8
KH = 0 (I add one drop of the API solution and it goes from clear to yellow immediately)
Nitrate = 0-2.5
Nitrite = 0
Ammonia = 0
Phos = 0

I make R/O water since I find a lot of fluctuations in my well water. The R/O water has a pH of 6.2 or less (the pH test kit only shows down to 6.2).

Yesterday, I made 32 gallons of R/O water and added in some Seachem Replenish. The GH is now 4, the pH is 6.4, and the KH is 0.

Is there any benefit of adding in the Seachem acid and alkaline buffers I have to generate some KH in the R/O water while still looking to keep a slightly acid pH for the fish I have?

Is the GH in my tank affecting the tetras?

Are cardinal tetras any hardier than neon tetras?

My clown loaches do well and I don't want to disturb them by changing this too much in the tank. My focus of the tank is the clown loaches (the big ones will eat food out of my hands). However, my son likes the different tetras and they get along with the loaches.

Thanks for the help!
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post #2 of 5 Old 07-19-2011, 07:20 PM
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Diagnosing a health issue is often very difficult. Internal problems are usually undetectable until the fish just dies. Prevention is the best "cure" and this is mainly achieved by avoiding stress as much as possible. Fish experience stress from many things: water parameters, other fish in the tank that may be less than suitable, overcrowding, excessive water movement, light-coloured substrates, too much bright light, noise, high nitrates, etc.

There are several things that I can see causing stress. Individually each may not be too great of a factor, but collectively it only gets worse. You asked for help and I will do my best to provide it, so please don't take this as just criticism of this and that. The fish's health is the concern.

One thing that stands out here is temperature. Neon tetra are cooler water fish by which I mean low to mid-70's. They will literally burn out above 77-78F. A degree or two may not seem like much, but to the fish who must remain in the water permanently with no means of escaping, it takes its toll on their metabolism and this is stressful. Red Eye Tetra would also be better slightly cooler. Even the Pristella would be better in the mid-70's. I realize the temperature range in the profiles for these latter two tetra goes to 79F and 82F respectively, but there are other factors at work in this. Loaches can tolerate higher temps but don't need to, so 77-78F would be better all around.

The second problem is that tetra are shoaling fish, as indeed are loaches. These fish must be in groups, the more the better, though for tetra 6 is usually considered minimum. Not only is there security--either real or perceived--for the fish in numbers, but these fish often have a social structure and interactions between members of the group that they naturally expect. [I am sure you have witnessed this frequently with your loaches, one of the most social fish in aquaria.] Being on their own or even in 2 or 3 denies them what nature intended, and that is highly stressful.

However, we come to another problem here, tank size. I realize your clown loaches appear to be doing well in a 40g, but that is really too small a space for a fish that can (or should) attain more than a foot in length. It may not be evident, these things usually are not, but long-term this is hurting the loaches. There is so much to this aspect i scarcely know where to begin, so I will leave it. Five is a good group for loaches, but this species should be in a 5 or preferably 6-foot tank. You can read more in our profile, click on the shaded name Clown Loach.

You should be doing much more frequent water changes. You don't have live plants (these would help with the water quality a lot) so there is no way of removing the buildup of toxins and pheromones from all these fish except more significant water changes. I would recommend half the tank volume every week, no less. Some others may suggest more than once a week in so small (to the fish) a space, and I couldn't argue. But it is best to work up in stages.

How exactly is your well water unstable? Another source of stress is adding chemicals to a tank, and I am not a fan of using water adjusting substances in an aquarium with fish. If the water must be prepared first, do it outside the aquarium and then add consistent water at each water change to avoid fluctuations in hardness and pH and help maintain a biological stability. The fish you are maintaining are all soft water, very soft water, and leaving it soft would be better than fiddling with it. Let the pH drop if it likes. With regular partial water changes of 50% weekly this will not be an issue. It isn't in my tanks, and I have a lot of fish in them with water that is < 1 dGH, 0 dKH and pH at 5 in some to 6 in others. All wild caught soft water fish.

I hope this will help.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #3 of 5 Old 07-19-2011, 08:01 PM Thread Starter
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Thanks, Byron!

I dialed down my heater to the 76 setting and I will see where the water temp settles out.

I have been thinking of getting a bigger tank.

I will look to restock my tank with more of the tetras.

My well water usually reads a pH of 76.-7.7, with GH of around 7-8 and KH of ~3-4. I have found it easier to use the R/O water and add in some Replenish to get the GH and the pH up slightly to the numbers I posted previously than to try to mix the tap water and the R/O water to get the numbers. Perhaps I should try again with the tap water:R/O water mix without adding in chemicals. I don't add any chemicals directly to the tank. I have a 55-gallon container I use to put the R/O water in and then I pump it into the tank after I do any cleaning and water changes.

It would seem letting the pH go down to even 6 with a very low GH and KH won't hurt the fish I have.

Regarding the water changes, I will do larger volumes each week than I have been doing.

I will look at prior posts on this forum about live plants to use. Seems more interesting than the plastic and silk plants I have now in the tank.

Thanks again for your help!

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post #4 of 5 Old 07-19-2011, 08:06 PM Thread Starter
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I have tried not to use just straight tap water given the pH reading of the tap water (I have even let the tap water sit for 24 hours and rested it, not noticing any significant change in the pH reading - maybe a 0.1 change at most) and the pH of the tank. With weekly water changes, I don't want to get the tank pH up too much and affect the fish.

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post #5 of 5 Old 07-19-2011, 08:29 PM
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Jeff, I agree with mixing RO and well water, sorry if that was confused previously. Its adding the chemical stuff I don't recommend.

I agree that lowering the hardness and resulting pH would benefit your fish. Work out the correct balance to get the pH acidic, just below 7 is fine, the rest will sort itself out. When i say work out, this means in the tank obviously, as the biology of the tank will result in a lower pH once the water is relatively soft. Mixing RO with harder water (tap or well) will dilute the hardness in proportion; example, half tap/well and half RO will cut the hardness in half, etc. Monitor the pH in the aquarium daily, always measure it at roughly the same time of day since there is a diurnal shift in pH and this might confuse the issue. The pH will lower on its own, this is not an issue for the fish.

If you want some background info on hardness and pH and haven't yet read it, I posted an article on this in the Freshwater Article section. May help to clarify.


Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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