I'm Putting Together a 40 Gal Tank - One Step at a Time

[dustin_P74]

i would say its probably a combo of the remaining city water, the instant ocean and the sand water that all added to it

 

[1geo]

I took the carbonate Hardness, KH reading, on the tank this morning and it has creeped back up to 15 from yesterday's 13. The only source of alkalinity has to be the sand. So, instead of a 10% water change tomorrow, I'll do a 20% change and keep monitoring. Hopefully one of my PH meters comes today so I can get a more accurate reading and plan a better strategy. Geo

 

[ccCapt]

Your alkalinity can't increase without adding something to increase it. I would suspect testing error if it just rose overnight. The sand does nothing as far as buffering, unless your pH is below about 7.3 where aragonite starts to dissolve. Just think about how a calcium reactor works. co2 is added to lower the pH so the aragonite media can dissolve. Aragonite does not dissolve at higher (8+) pH and will not add any alk or calcium to the system.

 

[1geo]

It is conceivable that the test kit is in error. Yesterday and today I ran the KH test more then 3 times and came up with the same readings so I question if its the test. As for the PH, there I have a problem. The PH is definitely higher then 8.0 but how high is anyone's guess. I can't distinguish between the high level color readings. I have two different PH meters on order and hopefully one will come today. It will be interesting to see what the next 20% water change does. The only other factor that could be part of the problem is the salt as dustin suggested. On the next water change I will take a reading of the RO water with salt in it to determine its KH before adding it to the aquarium. Fortunately, there is nothing but sand in the aquarium so I can take some radical steps to correct the problem without worrying about stock. Geo.

 

[yote]

A KH reading of 15,usually isnt going to hurt anything.It does seem to slow the growth of hair algae.But once coralline starts growing,the KH will start dropping a bit.
As long as the calciums good,let the KH ride.

 

[dustin_P74]

i would suggest taking your a big bottle of water to some LFS's for some testing

 

[1geo]

Both dustin and yote offer good suggestions and I'll take them both. I just took a bottle of RO water which tested zero for alkalinity raised the specific gravity to 1023 with Instant Ocean and retested for KH. It came out with a KH of 11. This was not good news. What that means is, with a present KH of 15, I would have to do a 100% water exchange to get the KH down to 11. A 50% water exchange would only get me to a KH of 13. So my immediate reaction is just to monitor the tank, see where its going and then decide how much exchange of water I want or more specifically need to continue on. If 15 is acceptable, then adding RO water for evaporation in the tank will eventually bring the KH down. One thing this test does tell me is the salt is not the cause of the 15 KH reading; that only leaves the sand. I've got 25 days before my live rock is shipped so there is plenty of time to decide what if anything to do. Geo.

 

[ccCapt]

Geo, I think your over reacting to a non existant problem. 15dKH is high, but there is nothing in your tank that it will affect. I may have missed it, but I assume you filled your tank when you started it with tap water? I would say that is the reason for the high dKH. Instant Ocean testing out to 11 dKH is right about what you should get at 1.023 with that particular salt. Just get into a routine of doing water changes and it will gradually come down. IO is a very good salt.
Trust me, the high dKH is not from the sand unless you filled your tank with freshwater, let it sit for a few days with only aragonite sand and freshwater and then added the salt. It is chemically/physically impossible for aragonite to dissolve in your tank at typical saltwater aquarium pH readings of around 7.8 - 8.4. And unless your injecting co2 into it, your in that range.
Are you going to cycle your tank while you wait for the live rock? Just throw a piece of fresh shrimp in to get it going?

 

[1geo]

Thanks ccCapt, I'll try the shrimp. I just took another KH reading on the tank and it has now creeped back up to 17 KH; the last reading I took was 8 hrs ago. I have a 3.5 inch sand bed in this tank which I think is overkill. 2 to 2.5 inches would be plenty. So I am mulling over the idea of removing 1 inch of sand and storing it in a 10 gal tank until I can prepare and use it in my 20 gal clownfish tank. I'm still not convinced that its not the sand, it could be something else in it besides aragonite dissolving. Right now I am waiting for the tank to reach a peak of alkalinity before I do anything. Once it stabilizes then the first thing I will do is a water exchange and maybe remove some sand. Geo

 

[ccCapt]

Something is not right. To raise dKH from 15 to 17 in 40g of water, you would need to add 2 teaspoons of baking soda or 29ml of SeaChem Reef Carbonate.
Have you tested calcium and magnesium?

Here's a great article for you to read.
A Simplified Guide to the Relationship Between Calcium, Alkalinity, Magnesium and pH

 

[1geo]

Calcium is 300 ppm and I have no test for magnesium. Today's reading are much like yesterdays, in the bottom of the tank near the sand the KH is between 15 and 16. At the discharge of the bio filter into the tank the KH is a strong 17. I don't know if these variations in readings matters; it maybe much to do about nothing. Still, it would suggest that a possible source for the increase KH is the bio filter. I purchased this filter used and when I got it, it was all cleaned up. It is possible that the seller used something to clean up the bio balls that is now leaching into the aquarium water and raising the KH. I know that is a long shot but just thinking out loud. In any case, the KH seems to have stabilized at this level, between 16 and 17. I do a 5% to 10% water change on the weekend and will post the results. One questions, is there an optimum sand level? Right now I have about 3.5 inches of sand. Is this level OK, to much or to little? Is it possible to have to much? Geo

 

[dustin_P74]

3.5 inches of sand is too sallow to act as a deep sand bed so its just for looks at that level. and the calcium is pretty low, you should aim for 400-500ppm but the calcium being that low wont affect anything in your tank right now since there is nothing in there but sand

 

[ccCapt]

You are bogging yourself down with all these tests. The readings you are getting make no sense. There is no way the water has a diff alk reading from different parts of the tank. Did it take the entire last drop of reagent to get to the endpoint color, or would 1/4 of a drop been enough? You are reading your tests in dKH, but how about meq/l? Can you tell if your at 3.9 meq/l or 4.1 meq/l? Do you see my point? Don't get so wrapped up in testing.
Your alk is rising, yet calcium is dropping. If the sand, as you suspect, was causing the rise in alk, it would also raise calcium. IO typically runs about 360-380 calcium.
I'm not sure what brand test kits you are using, but I highly recommend Salifert. Very easy to use and very accurate.

Also, please read the article I liked to earlier. ;)

 

[dustin_P74]

capt if he has 380 calcium in the tank when he fills it up with saltwater and then adds just sand why would his calcium drop 80ppm?

 

[ccCapt]

Exactly my point Dustin. It can't happen....unless he saw a major precipitation event, but then that would also drop alk. None of the readings (alk & ca) make any sense.

 

[Bifferwine]

3.5 inches of sand is too shallow to house any beneficial anaerobic bacteria, but deep enough to trap detritus and gunk and crap. Ideally, you want an inch on the bottom since that's the best depth for your cleaner crew to keep clean. If you keep fish that use the sandbed as their habitat, you need to increase it. It really takes a minimum of 6 inches to get anaerobic bacteria living in it, and even that number is probably more like 8 or 10 realistically.

 

[1geo]

Today I did a 10 gal water exchange on my 40 gal tank, actually with the sump its 44 gal. After letting it circulate for 3 hrs I took the KH levels which were down from 17 to between 14 and 15. If they stay there until tomorrow I will know I have the alkalinity under control; if not, they I’m still looking for the source of the alkalinity. Yesterday I cleaned the skimmer on the wet/dry filter and found it had about a cup of yucky smelly stuff in it. Which tells me there a proteins in the water probably from the sand and the Nitrites showed a small increase from zero to between .25 and zero. Tomorrow I will check KH again and hopefully its still below 15. Geo.

 

[1geo]

I agree that the chemistry is screwed up. I am not a novice as far as water chemistry goes. Years ago I was a senior reactor operator on a CA reactor. I have taken years of titration and colorimeter tests on water samples. Still, I agree the results I am getting make little sense but they are accurate with in the limits of the API kits. Soon, I hope, I will have a digital PH testing meter and a Salifert kit to test KH; until then, API will have to do. The latest calcium reading, after the water exchange, is 320. Geo.

 

[dustin_P74]

i would take API test results with a grain of salt (no pun intended)

 

[1geo]

I forgot to tell ccCapt that I read the article he referenced and even download it to Word for future reference. I also bought the book,"Marine Chemistry" by Brightwell which is excellent. Its written in a manner a non-chemist can understand. He discusses test kit accuracy and states that the cheapest ones are the least accurate, i.e., API.; if I could afford a Hach colorimeter I'd be in business. Geo.