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Thread: howdy from the uk - day one

  1. #1
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    howdy from the uk - day one

    thought i would chip in and let you comment on my effort so far.
    Backgroung of display- 5 x 2 x 2 with 240 ltr sump containing skimmer (massively inefficient), DSB in display (silica play sand), approx 100 kgs live rock.
    Most corals are 7 years old and all fish but 2 of the tangs, are of similar age.
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    I have always been interested in the algal screens as a method of saltwater maintenance but until now havent been enthused enough to try a proven method. Now is the time, mainly because my stock are requiring more and more good quality food stuffs.
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    I feed 5ish (santa monica food units) per day, plus a diy coral mush twice a week.
    The screen is 13 inch by 6 inch. At the moment only 50% of the screen is lit, both sides by a single 23watt cfl each side. Gonna be putting lights on the other end of the fitting very soon. Flow is 2500lts hour.

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    Let's watch that growth

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    Curious, how did you manage to get away with using "silica play sand" in an aquarium setting and not have constant algae/cyano problems? I had a silicate problem in the past due to using bad RO water and it took months to remedy using special silicate removers, and that was just using bad water for a water change.

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    Quote Originally Posted by Ace25 View Post
    Curious, how did you manage to get away with using "silica play sand" in an aquarium setting and not have constant algae/cyano problems? I had a silicate problem in the past due to using bad RO water and it took months to remedy using special silicate removers, and that was just using bad water for a water change.
    I did a fair bit of research on the solubility of silica sand in salt water and there were 3 distinct points of view.

    1) the people using expensive aragonite type sand said that a silica bed would be disastrous.
    2) the people using silica sand ( bar a few exceptions ) said they had never had any problems.
    3) the chemistry trained people said that silica sand was nearly inert in salt water.

    So I went for the cheap silica sand and have never had any problems.

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    9 year old article on the topic.

    http://www.advancedaquarist.com/2003/1/aafeature1

    In the first experiment I took 3 cups of sand, and suspended it in 3 gallons of freshly made Instant Ocean salt mix that initially contained less than 0.8 mM of silica (0.05 ppm SiO2). After 48 hours of gentle stirring with a powerhead (the water was stirring, but not the sand), the silica concentration had risen to 17 mM (1.0 ppm SiO2).

    I then rinsed the same sand 5 times with 1 gallon RO/DI water (1 minute each time), discarded the contents, and then ran the same stirring experiment with 2 new gallons of Instant Ocean salt mix. In 48 hours the silica concentration had again risen, this time to 15 mM (0.92 ppm SiO2). Then I let it sit unstirred for another 96 hours, and the concentration had risen more, to 23 mM (1.4 ppm SiO2).

    In a different experiment, I took about 45 pounds of sand, and added 2 gallons of Instant Ocean salt mix. I let this mixture sit for 7 days, with once a day mixing with my hands for about 30 seconds. At then end of this test, the concentration was 90 mM (5.4 ppm SiO2).

    It has been suggested that the amount of silica coming from calcerous sand might actually be as high or higher than that from silica sand. To test this hypothesis, I repeated the small-scale experiments above on a calcium carbonate sand from Home Depot (Southdown). In this case, there was some soluble silica released after the first 48 h, but only 1.6 mM (0.1 ppm SiO2), or about a factor of 10 lower than the silica sand. In a long-term test, the concentration had only risen to 5 mM (0.3 ppm SiO2) in 14 days with once a day stirring.

    From these experiments, I conclude that:

    The “silica” play sand that I purchased from Home Depot can substantially raise the dissolved silica concentration in seawater.
    The dissolvable portion of the silica sand cannot be completely removed by several rinses with either fresh or salt water, although it may be decreased somewhat by that process.
    Southdown calcium carbonate sand (likely aragonite) can release soluble silica, but about ten fold less than the “silica” sand.

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    Ace 25 - good point.

    I've read a lot of Randy's work (tests quoted) and this is the main evidence I used to determine whether or not I would risk it, or not. The next few paragraphs of his work is most interesting to me. Especially about perhaps dosing silica in reef tanks because so many organisms in the tank utilise it. I guess a silica bed will mean that I will not have to dose. Another benefit of silica sand?
    I guess the specific type of sand I used must be just right for my tank.

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    Remember that diatoms can't grow without N and P, so regardless of the silica, if your scrubber is working you should not have problems.

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    I used pool filter sand (silica type) in the bottom of my 40G and put crushed coral over the top that and kind of sifted it into the sand a bit. I have done this several other times without issues too. I have heard both sides of the fence on this but I can only relate to my experiences. One question I have is how would the silica come out of the sand?? Is silica part of the sand?? I have always been confused on this subject.
    150G. Reef/Mix
    125G. 3 Regular Oscars/1 Jack Dempsey
    75G. 20+ Africans
    40G. Fish/Reef. Algae Scrubbers on ALL my SW
    10G. SW Fish/Reef.
    10G. SW Hospital/new fish quarantine/pod breeder tank
    6 stage RO/DI system 200 GPD.

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    Silica sand = Quartz rock crushed up into sand particle sizes
    Aragonite sand = Calcium Carbonate rock crushed up into sand particle sizes

    2 completely different types of rock crushed up to make the "sand".

    Anyway, I wasn't trying to derail the topic, I was just curious if Garf has seen any issues with using Silica sand since I see far more people that have issues than don't, but like he said, some silica sand can be better than others, rinsed more, and not release nearly as much silicates as other types. Only way to really know is to do a test like Randy has done.

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    Update on scrubber screen progress after 24hrs.
    Going BROWN as expected.
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    I am going to try a post regular pictures from a similar angle to document the evolution of this screen. I,m hoping to complete the lighting set-up in the next few days.

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