Water Chemistry Questions

[dmurray407]

I spent the weekend reading up on water chemistry. My tapwater is very hard and full of "stuff" so I decided several years ago to start using reverse osmosis water from the Culligan machine at my local Walmart store. This morning, I did several tests on my water using both a test kit and some test strips-the results were actually very similar, though a little more precise with the test kit. Now, I'm not sure what to do next, so maybe someone here can help me out
Tap Tank Culligan Aquafina
pH 7.5 6.0 6.0 6.5
KH 240 0+ 0 0
GH 160 120 0-30 0

(I hope this chart makes sense-I tried to fix it so the columns were aligned, but couldn't get it right)

My nitrite and ammonia are fine (0) in my tank, my nitrate is high but I'm working on it by doing 20% water changes every other day until it comes down (a question about that later).

What is making my GH so high in my tank? Does that really matter? Will the frequent water changes help correct it? Also, I would think it might be beneficial to raise my pH and KH just a little, but know that any change in either one will affect the other. I read that you can raise the KH by adding a little (1/2 tsp per 100L) baking soda, if I did that how would it affect the pH? I would be adding a base so would it make my pH go up a little, too? Should I do this? I have my one very hardy Angelfish in my tank and don't want to hurt him by changing the pH too much. When I get my nitrates down, I would like to add some tetras and loaches as well, so my goal would be to have water that would make them all happy.

My question about the water changes-I'm changing out 20% and cleaning the filter (Fluval cannister) every other day this week and for however long it takes to get my nitrates down. My tank is 26 gal, so I'm doing 5 gallon changes. Since it's RO water, I normally add some Kent RO right and aquarium salt back in to replace minerals. With the frequent 20% changes, do I need to replace the minerals every time? Does this even make sense?? I'm very curious to hear your suggestions/thoughts on this-
Thanks!
Deb

 

[BillD]

What are the parameters of your tap water? Are you using strictly RO water for the changes? You might want to do bigger changes and mix tap and RO or go strictly with the tap. Ph is not usually a concern as most fish are very adaptable, Domestic angels do fine at pH or even higher.

 

[BigJim]

First, why are you concerned with your water quality? Unless you're trying to keep difficult fish like discus or wild angels, you'd probably be ok just using the tap water. I've never tested my tanks for hardness, but my pH holds between 7.0 & 7.5 and I've had many species of fish breed in the tank.

What are you using for substrate and decor in the tank? The aquarium salt may also be causing the high hardness.

pH is the most overrated water parameter in your aquarium. Most fish will adapt. I wouldn't mess with it if the fish are doing well.

If you're removing water, you're removing minerals. If you don't replace the buffers, this will happen:

1st 20% PWC - 80% of the buffers remain
2nd PWC - 64% remains
3rd PWC - 51% remains
4th PWC - 41% remains
5th PWC - 33% remains ...

You'll destabilize the system and make it susceptible to pH swings. Fish will adapt to different pH, but they don't like pH swings.

 

[BigJim]

A second group of thoughts: What are your tank parameters? Why are your nitrates so high? RO water shouldn't have nitrates. What is your stocking list for the tank? Do you have plants? Anything decomposing in the tank?

 

[dmurray407]

The nitrates are my fault-feeding my one fish too much and not frequent enough water changes. Right now I have a fairly coarse aquarium gravel on the bottom. I had a large sandstone rock (bought at an aquarium store) so I'm sure that could have leached into the water a bit-it's been out for about 1 week. Now I have a piece of driftwood in the tank. I stopped using my tap water because the LFS owner told me that the only thing I should really be able to keep in my tap water were Cichlids and I wanted something different. That said, I think the entire state of MN has similar water and I've seen some gorgeous aquariums here.

I haven't had plants for a few years-I plan on introducing some when I get my nitrates settled-before I add any new fish. I made a list of plants to start off with-Crypt. walkerii, Vals "corkscrew", Java Fern and Blyxa aubertii. I have some alternates in case I can't find the ones on the list: Anubius congensis, Crypt. wendtii, Echinodorus bleheri, sagittaria sublata (please excuse my spelling) Any suggestions in this area are welcome. I have a 55w compact fluorescent light (50 daylight and 50 actinic blue) so my light isn't super high and I don't have a supplemental CO2 source.

Do you really think the tap water would be OK? It's a lot of work carrying all that water back and forth

Should I continue with the appropriate amount of Kent R/O and leave out the aquarium salt? It has always seemed a little redundant to me to add the salt, but LFS person said I should, so I do . . . (and, for future reference, if I use tap water I don't need to add anything, right?)

The reason I'm concerned about my water quality is twofold. One, I want my fish to be healthy and two, I know I messed up with the nitrates and want to get it corrected ASAP-and besides, it's kind of fun using all my little test tubes and chemicals

Thanks! You guys have been very helpful answering all my questions-I truly appreciate it!
Deb

 

[BigJim]

Does the LFS use all RO water?

There's no reason to solve your nitrate problems before adding plants. Plants can help reduce nitrates.

I wouldn't switch to your tap water immediately. If you start mixing tap water with the RO water, increasing the tap water concentration over time, I think you'd be ok.

The salt adds electrolytes to the tank. It's good when your fish are really stressed or ill, but it affects some fish badly. I don't run salt much. If you go with straight tap, there's no need to add anything other than dechlorinator.

 

[dmurray407]

Actually, the "LFS" just closed it's doors-though it has been there with various owners for many years. She usually had a nice selection of fish, but was mostly a bird/snake person. Good point-I can't imagine that she ever used anything but tap water. Maybe I'll go on a plant shopping trip later this week-I found a few nice looking stores in Minneapolis that I would like to check out.

Thank you
Deb

 

[BigJim]

I think your best plan of action would be to find a good LFS if possible and quiz them about their tanks and water. If they use tap, I don't think you'd have any problems if you convert the tank over slowly.

 

[jsoong]

Pure RO is not good for your tank ... there is no electrolytes, and no buffers (ie KH=0), so it is prone to pH crash.

If you must use RO, you should either mix in a fresh water buffer salt, or mix in part tap water to maintain a safe KH level. <You should have at least KH of 40 or 50 to ensure stable pH.>

Having said that, your tap is not bad at all, just about the same as mine. Unless there is something else in the tap (heavy metals, nitrates, etc) you should be fine using tap. It is best to check with a good lfs, a local fish club, or your water co to see what is in your tap water to make an informed decision.

If you want to switch over from your current RO to tap, you should do so slowly so the fish can acclimatise. A super-safe way is 10% per pwc, every 2-3 day (or week).

 

[XimeD]

+1 on switching to tap water (gradually as was suggested)

I have pretty hard water myself pH 7.4, KH = ~100ppm and gH = ~300ppm and have had no problem whatsoever with it, I even kept cardinal tetras for a while and they were fine (the LFS I bought them from also uses tap water)

+1 on keeping plants for nitrates (I have to dose nitrates in my tanks cause my plants will keep nitrates at 0 if I don't, 0 nitrates is not good for plants)

 

[ChizerBunoi]

My tap water is very hard and has a ph of 8.4. Those plants that you listed will do fine in them. Unless you purchase fish that were used to a certain water parameter, there is no need to buffer the water and reduce to a certain level.

Don't just go by what one local fish store owner says. Most of the time, they don't have your best interest in mind. Remember, they are out to make money and keep you coming back.