water chemistry


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I have been playing the pH/ alkalinity/ calcium runarround game (I know, I know) I am testing and kalk has been tough to use to keep up with the ca levels without over diluting the salinity. Marine buffer worked for pH but raises alk too high and ca falls. Now I am back to kalk to supp ca and help control pH. I think I run acid because my berlin diy skimmer isn't doing enough. (pH =7.9-8.2), Ca 300-450 (I am working on the 450 range). Alk 9.4-12.5 and sg 1.024. Nitrates are 1-2, nitrites, amonia are zero and phosphates are <<.1. I have not tested magnesium. Pump is a mag 900 and a power head with associated hydrostatic load I get about 600g per hour of circulation. Live sand bed 3-4inches display, 5 inches refugium.

I have a coral garden with mushrooms, favites, a dendronephthya, euphilia species, some zoanthid polyps, nemenzophilia and alveopora. 72g bow front with 30g sump and 9 fish under 2 inches each. Live rock fills about 1/3 of the overall volume. The tank is 7 months old. I do 2-3 5g water changes per week with IO salt aged 24-48 hours and ph matched with sea chem marine buffer made with ro water (the solution to pollution is dillution). Here are my questions:

What is a good in sump skimmer that I can add to the existing skimmer (which puts out but not in large quantities). (would like to stay in the $2-300 range and not have to fuss with the output valve too much)

I have looked at your technique in BCP1 of adding kalk slurry (1/16 tsp mixed in ro water) daily. Do you actually let the powder go in the sump/tank or do you decant the limewater like usual? I will be monitoring calcium to see what the daily requirements are once I get things stabilized in a good range.

PH has been a problem I feel like I barely feed the fish and I have a refugium with callerpa and still pH falls nightly to below 8.0. (Refugium is lighted at night). Could the skimmer be the problem?

Finally, I have on the back of the tank very course calcium like white deposits that are clearly different from the coralline algae growing in some areas. Is this a water chemistry nightmare, or are the deposites something I should work hard to scrape off? In my mind it looks like calcium carbonate on the glass. I also get flaky calcium like deposits in the sump which I suction out once a week. Help!

Sorry for the long question but I need to find a way to stabilize so my animals don't suffer the sometimes dynamic swings my inexperience is imposing on this system! My gut tells me I am tweeking the system too much. Oh, the pH on my ro water is 8.8 and on my fresh salt mix before adjusting is 7.8. This seems strange. Shouldn't the RO water pH be 7.0 or lower if carbon dioxide is dissolved? I do airate all water in storage. Thanks



"Better is the enemy of good"
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Cheers, Ron

No worries... as confusing as this all seems, it is easily resolved. In a phrase: "Dilution is the solution to pollution." :) Lets begin my friend by getting your skewed chemistry (from seesaw dosing activities) back to an even keel. Stop testing or worrying about ideal levels and have faith that several (2-3) large water changes (35-50%) in the next two weeks will help to get you back on par. It shoul;d go without saying that the new seawater must be properly/carefully adjusted in temperature, salinity and pH - never estimate this on a water change of any size.

Such problems (seesaw) occur because many/most of us are aquarists with little or no grasp of chemistry. Furthermore... most of us again are American men that are obligated to resist reading or asking for directions to anything ;)

Do consider taking the time to read the excellent and lucid articles and threads (here on RC, over at Reefs.org, and follow biblios) of Randy Holmes-Farley. Outstanding and concise.

I have a beginneroriented article "Understanding Calcium and Alkalinity" over at wetwebmedia.com (use google search tool or navigate to marine topics from the home page... lotsof good content over there too)... which is not only for beginners and also addresses pH and kalk use.

One thing you need to understand right away is that the target numbers bandied about on message boards such as this are from advanced aquarists with diffrent needs than those who have an average (and under-stocked/properly stocked) reef display. FOlks can get caught up in a race to acheive unrealistic high end ideals of ranges such as Ca, ALK and pH that are not useful or safe for most aquarists to pursue. Simply know that consistency withing the safe range is much more conducive to optimal reef health than occasional spikes to the high end.

To be specific... Calcium is fine anywhere between 325 -450. And Alk is just ducky in the 8-12 dKH range. But both are not intended (or likely) to be kept stably at the high end of both ranges concurrently. If you have 450 ppm Ca, then you will be just fine at 8 or 9 dKH.

And if yo are having trouble getting to 450ppm Ca... no worries. I can assure you that your reef will fare better and grow faster at 350ppm calcium if very stable, rather than a daily rollercoaster ride from 350 to 450.

Kalkwasser IMO is the best and most inexpensive way to provide Calcium and indirectly support Alkalinity (little or no buffer may be needed with proper Kalk use). Reread the passage again my friend (and check out the many FAQs on wetwebmedia.com on this subject). I can't speak to your use of it as correct or in need of tuning until you test and know your daily need for calcium. And yes, for some aquarists... the "powder"/slurry is to be paced directly into the tank in a strong stream of water because the supersaturated solution (sans precip) does not bring enough calcium in to meet the daily demand (confirmed or denied by that test you need to do ;) regarding daily demand).

For a very good and affordable skimmer, I am quite certain that you will be delighted with an Aqua C or Euroreef brand skimmer. Both are very efficient and excellent values... I would take them over an over-proced and over-engineered downdraft style skimmer anyday. They are much easier to tune/use and clean too (a miserable flaw to the latter mentioned).

The flaky deposits in your sump are perhaps precipitating insoluble caclium carbonate from your abused seesaw use/dosing of supplements. The water changes will stave this. And continuance of properly dosed (measured/tested/metered) calcium hydroxide (kalk) will prevent this. Else, the use of a two part supplement may be helpful (more expensive though). Bear in mind though that the system needs to be in balance before you can expect a "balanced" two-part supplement to carry on the job.

I favor kalkwasser for its many other benefits. A calcium reactor well-tuned is a great benefit too if/once affordable.

Best regards,

Thanks for the detailed reply! I read the links and will start the water changes (I am currently set up with 2, 5g salt water sources both circulating with power heads, one with airation, circulation and heat) My salt water starts with ro water pH 8.8 but low alkalinity and with IO salt mix ends up pH about 7.8. Should I adjust pH of the new water with kalk slurry or a buffer before water changes? I will not be getting a calcium reactor soon (tuning is an issue but more importantly, convincing the better half). I will be spending the money on a second skimmer. Thanks again for the advice!!

One more quick question, should I vacuum substrate with each water change? I have been vacuuming only every other week or so but I do frequently (every other day) turkey baster blast off rocks, substrate etc. Thanks again, I'll tell you how it goes.

By the way I have some great microscopic movies of my dendronephthya polyps moving, catching particles etc. Time lapse seems too slow but I have tried it. If you are interested and I get good results, I'll burn some movies on CD for you, they are too big to e-mail with good quality though. Thanks again

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the high RO water pH is very curious (uncommon). Have you tested your source (raw) water? I would expect it to be as high or even higher if the reading is accurate.

At any rate... good aeration of the ro water (overnight)... then salting (more mixing... over night)... then buffering with a little seabuffer will likely be fine.

The decision to vacuum the substrate depends... with fine sand and adequate water flow (10-20X minimum)... little or no striiring is needed IMO. But with coarser media and/or lesser water flow... vacuuming and strirring may be necessary, indeed.

I would definitely love to see pics/video of your feeding neptheid when they are ready... fascinating stuff! :)

Thans kindly,

Wow, my meter callibrates perfectly to three levels, pH4, pH7 and pH 10. The reading directly from my basement tap is 8.3, the same result upstairs. Cold water tap I wonder what my family is drinking :confused: . I'll call the water authority on monday!

Three water changes of 7 gallons and my system is seeking the normal ranges. I will do a few more over the next 2 weeks then assess daily alkalinity/calcium requirements. I must say it is great to ask questions of the experts and get timely replies! My inverts thank you :D and so do I.

I'm not sure about the expert part ;) but you are very welcome, and I/we do enjoy sharing advice and opinions!

with kind regards,