# Substrate bacteria?



## Tomagorn (Apr 5, 2013)

The past couple of times that I have done water changes, I have noticed a black cloud whenever I move the plastic tube through the gravel. The cloud is quickly removed by the siphon, but I'm wondering if this is unusual or dangerous for my fish. The cloud is only black in my 29-gal aquarium. My fish seem healthy, though over the past month there have been two unexplainable deaths (a cory and a blue ram). In my 10-gal aquarium there is a similar cloud but it is a light gray. Both tanks have the same gravel. Parameters in both tanks are similar: pH 6.8-7.0, ammonia and nitrite 0, nitrates around 40 ppm, kh <100 ppm, Temp 78-80. I keep sea salt in the aquariums at about 1 teaspoon/gallon, mostly because 75-80% of my replacement water is distilled. Water changes are ~30% every 10-14 days. Any ideas or suggestions? Could the black cloud be anaerobic bacteria?


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## walzon1 (Jun 17, 2013)

By plactic tube are your referring to the siphon tube when you are siphoning your gravel? Also I don't understand why 80% of your tank water is distilled and why you are adding sea salt, what is your reasoning behind this?


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## Tomagorn (Apr 5, 2013)

Yeah, I'm talking about the large hard plastic tube at the end of my siphon hose. I try to stir up the gravel to make sure I get any detritus.

My tap water has a pH of 8.2+ and a Kh of >100. Since my SA fish like much lower pH and less Kh, I turned to distilled water which has a pH around 6.0 and virtually no hardness of any kind. Of course, fish would die pretty quick in distilled water, so I add the sea salt to provide sufficient electrolytes. Pretty much every aquarist I know adds salt to their freshwater aquariums no matter what their water source is. My level of 1 teaspoon per gallon is a little higher than the usual prescription (1 tablespoon per 5 gallons), but I'm starting with almost no electrolytes.


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## walzon1 (Jun 17, 2013)

I generally don't recommend trying to simulate perfect parameters cause this can cause more fluctuations than just using tap water. Unless of course you are dealing with rare wild caught specimens or trying to breed and having problems you are better off just sticking with tap water.

The color of detritus is pretty normal but your fish losses could be caused by PH swings the salt doesn't give any buffering capacity. If you want to stick with distilled water you need a buffer rather than sea salt, because it has the buffers to keep the PH from swinging.


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## GTZ (Apr 21, 2010)

He may not need to buffer depending on where his KH/GH are after diluting the tap with distilled water. The salt will aid in osmoregulation, however, calcium and magnesium (GH) are vital as well. Depending on your GH levels after cutting your water, you may need to elevate these compounds. Epsom salt will provide magnesium but not calcium. 
Seachem Replenish is reportedly a good product to use with RO/DI water, however I don't have any firsthand experience with it.
Back to topic 
How thick is your substrate? Any rotten egg smell while vacuuming? Anaerobic bacteria can appear milky grey to dark grey. How often do you vacuum?


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## Tomagorn (Apr 5, 2013)

Thanks for the responses, guys. As I mentioned in my original post my KH is running just under 100. Sea salt, which is what I use, contains calcium. I do use a buffer (phosphate) but only because it is my dechlorinator for the little bit of tap water I use.


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## walzon1 (Jun 17, 2013)

Just to clarify are you using Sea Salt like the type you would buy from the market or a synthetic sea salt pruduct like Instant Ocean. I just assumed you were using the store type which doesn't contain significant calcium or magnesium to buffer at all.


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## Tomagorn (Apr 5, 2013)

Sorry, walzon1, I'm not sure where you're getting your data or why you're not seeing what I write. Sea salt from the market is simply evaporated seawater (or salt lake/marsh water) and contains all the trace elements of any sea salt source. There is as much calcium in it as there is in sea water. More importantly, as I have said twice above, my KH is running just under 100 ppm, which should be more than sufficient buffering. Finally, I just completed a test where I measured the pH in my 29-g tank at night just before lights out, when CO2 should be lowest and pH highest, and compared it to the pH early in the morning when CO2 should be highest and pH lowest. pH both times was identical at 6.8. So there is sufficient buffering


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## b3w4r3 (Dec 14, 2012)

It sounds like you need to do bigger/more frequent water changes. 40ppm nitrate is on the high side and you should try for 20ppm max before a water change. The black areas in the substrate are usually associated with anoxic regions which can produce concentrated hydrogen sulfide gas. When you vacuum these areas can you smell any sulfur in the collection bucket? How deep is the gravel in the tank? Anything more than 2 inches is too deep IMO.


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## walzon1 (Jun 17, 2013)

Tomagorn said:


> Sorry, walzon1, I'm not sure where you're getting your data or why you're not seeing what I write. Sea salt from the market is simply evaporated seawater (or salt lake/marsh water) and contains all the trace elements of any sea salt source. There is as much calcium in it as there is in sea water. More importantly, as I have said twice above, my KH is running just under 100 ppm, which should be more than sufficient buffering. Finally, I just completed a test where I measured the pH in my 29-g tank at night just before lights out, when CO2 should be lowest and pH highest, and compared it to the pH early in the morning when CO2 should be highest and pH lowest. pH both times was identical at 6.8. So there is sufficient buffering


Sorry if I misread your posts I do a lot of reading and skim through much, I thought your KH was the reading out of tap. Much of my info comes from reading articles and forums and talking to other hobbyist. I am definitely not a SeaSalt Guru nor do I understand the chemical transformation of dehydrating and rehydrating of ocean salts. What I do know is with my experience with Reef aquariums and through reading Reef forums the salt used is critical to fish and inverts and from my understanding even though sea salt from evaporation does have minerals once rehydrated the levels are not enough to sustain the required PH and Calcium levels of a Reef environment, which is why synthetic salts are formulated by adding addition minerals and trace elements to ensure it simulates a true ocean environment. If you have more info that I am not aware of, please feel free to enlighten me and share your info sources.


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## Tomagorn (Apr 5, 2013)

Thanks, "beware", for answering my original question. And thanks for the comment on nitrates. I have heard lots of different theories about how much NO3 is too much. I have reduced the stocking level in the 29-g tank and will do more frequent water changes. I have not smelled any rotten egg odor when I did any water change--and believe me it's a smell I know too well--but there may still be some H2S being produced. My gravel is about 2-inches deep, though, of course, it varies across the bottom of the tank. I don't think any area is more than 2.5 inches, nor any area less than 1.5 inches.


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## Tomagorn (Apr 5, 2013)

Just an update: I removed about half of the gravel, so overall gravel depth is now slightly more than an inch. Also added an air stone. I'm thinking that the anaerobic bacteria buildup in the gravel may have off-gassed some H2S bubbles that might have killed my cory and ram (both bottom dwellers). Hopefully the reduction of gravel depth and addition of air and bottom circulation will solve the problem. Thanks again for input.


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## RangerRift (Aug 10, 2013)

@GTZ - great post, and spot on! Tomagorn, I think the reduction of substrate depth and addition of an airstone are good step. Do you have a powerhead in there? It will help with general water column circulation, and will help keep too much detritus from settling on the bottom. That paired with larger and more frequent water changes (thumbs-up b3w4r3!) will solve your problem.

BTW, as I keep Africans, I'm incredibly jealous of your tap water params - wish I had 'em!

Keep us posted!


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## Tomagorn (Apr 5, 2013)

GTZ, since you raised the topic of hardness, do you have some rule of thumb guidelines for SA cichlids? Both KH and GH? I'm trying hard to understand these two topics, even though they have pretty straightforward definitions. GH is simple, Ca + Mg, as you noted. KH is a bit more confusing--sum of all acid resisting anions, which is primarily CO3/HCO3, but also includes things like PO3. And how do I know if I have enough/too much salt (NaCl), which doesn't show up in any hardness tests? Any answers will be much appreciated. Thanks.


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## GTZ (Apr 21, 2010)

I don't unfortunately, no. And I might add that SA isn't my cup of tea so to speak. However I can reference a couple of articles that deal with RO/DI and hopefully they'll cover what you're looking for.
http://www.americanaquariumproducts.com ... tml#amazon
http://www.aquarium-pond-answers.com/20 ... se_osmosis


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