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Sizing a scrubber based on feeding (guideline review)

Discussion in 'Basic Principles' started by Allen Repashy, Dec 12, 2012.

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  1. Allen Repashy

    Allen Repashy New Member

    Hello again,

    I am looking at the math given in the guidelines for sizing the scrubber and it doesn't seem to balance out when comparing dry feed to frozen at all. Maybe I am not visualizing what size a "Frozen Cube" is correctly, so please let me know what you think of these calculations. I manufacture foods, so I am always looking at things on a "dry matter basis" because that is how to compare apples to apples so to speak.

    Frozen food cubes are typically 85%-90% moisture. FACT
    My gel foods when hydrated according to the directions are 85%-90% moisture...

    So we can compare apples to apples in this regard.

    When I think if a "frozen cube" of fish food, I am picturing a cube the size that they are packaged pre frozen and ready to pop out..... hikari for example. This cube is about 1/2" square.

    Yet, the recommendations show that 1 "frozen cube" is the equivalent of 2.8 grams of dry pellets using a two sided screen.

    If I take 2.8 ounces of dry feed and hydrate it the same as a frozen or gel food, I end up with a cube that is approx 25 grams, or the size of a large ice cube made in a typical freezer tray.

    That is a LOT bigger than the frozen cube I am picturing.

    Can someone clarify the size of a "frozen cube" by weighing it. I am guessing it is probably five grams.

    So either the equivalents being used for dry food are way off, or the size of the cube you are talking about is way off in my head.

    At the end of the day it is aboutcomparing the amount of nutrients on a dry matter basis, and beyond that, the nutrient density of the different foods can also play a part.

    To figure the amount of dry feed by weight in a frozen cube, just weigh your average cube and multipy it by .125.

    If a frozen cube weighs 5 grams, then in this example, we are really only looking at about 625mg or .625 grams of dry feed...... and comparing it to 2.8 grams of pellets as equivalent in the guidelines.

    Cheers, Allen

    1 frozen cube per day (2-sided screen), or
    1/2 frozen cube per day (1-sided screen), or
    10 pinches of flake food per day (2-sided screen), or
    5 pinches of flake food per day (1-sided screen), or
    10 square inches (60 sq cm) of nori per day (2-sided screen), or
    5 square inches (30 sq cm) of nori per day (1-sided screen), or
    0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen), or
    0.05 dry ounce (1.4 grams) of pellet food per day (1-sided screen)
  2. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Good point Allen. I appreciate this viewpoint.

    You are correct, a "cube" is one of those Hikari or Ocean Nutrition cubes from a cube tray - about 1/2" or 1cm on a side.

    I did not come up with the "equivalent cube" figures - that was Santa Monica, and you are more than welcome to apply scientific reasoning and provide us with a more accurate estimate.

    The real test, of course, would be to have an experimental scrubber setup with a baseline per-day feeding and then vary the amount of feeding and view the resultant growth changes. Too many variables to make it a truly scientific setup though I would think. So we are stuck with educated guesses I think.

    What food do you manufacture?

    The food that I use is a DIY food which is a blend of different kinds of seafood, prepared foods, coral food, and supplements. I don't think it is quite 80-90% water though - because we make it ourselves. Our local club makes a batch of about 60-70 pounds of food every 6 months. It is very dense/concentrated, when I feed Rod's food that stuff seems to dissolve much quicker, our DIY Food takes much longer and has bigger chunks in it. Different batches of food seem to result in different variations of algal growth. So I know there is some factor that is overlooked.

    The feeding based guideline is exactly that - a guideline. It is not a hard and fast rule.
  3. Allen Repashy

    Allen Repashy New Member

    Hi Bud,

    If you look at whole live fish, squid, shrimp, plants, they all are around 80% water, so mash it up and you will find that if you add about 5% water, this gives you a workable slurry. Beyond that, nutrient density is the x factor..... for example, if you have one food that is 25% protein and 5% fat, and another that is 50% protein and 10% fat, you are approximately adding twice as many nutrients to the equation. Another x factor is the amount of organic/inorganic phosphates in the diet... if you have two feeds with the same protein and fat, but one has twice as much phosphorous in it, this will also have a major effect on the system. In tanks with a lot of feeding, this is probably why some people report nitrate is the limiting factor, while others report phosphates are limiting.

    You could have a food that is 40% protein and 2% phosphorous (those that use pyproduct fish meal) and another that is 40% protein and 1% phosphorous (one that uses whole fish meal) and you are going to be putting two competely different loads on the system.

    To start, Dry Matter Basis (DMB) is definitely THE way to level the playing field as much as possible. My previous example clearly shows that the recommended comparisons are off by as much as 5X

    I would recommend that you (I can help) revisit this and base the recommendations on converting everything to something like per gram of dry feed. (sub qualifying that with an "average" feed nutrient density of 40% protein, 8% fat, and 1.5% phosphorous (the average density of most good feeds)

    Looking at the numbers, you might say the L2 is good for . gram per day feed (DMB)
    Which would be the same weight of pellets, flakes, or powder.
    Or this would be a frozen/gel cube that weighed approx 3 grams (which is probably what a "cube" weighs...

    Given the cube size is correct, if the food was the same nutrient density, .5 grams of dry feed would equal a cube.

    which is WAY off from the guidelines of 2.8 grams dry feed equals one cube...... The guidelines look like they are just comparing dry and frozen on an equal weight basis and not considering that the water content is "empty weight"

    Cheers, Allen

    PS. I make a small line of high quality gel food premixes. They have been targeted primarily at the Freshwater market but some of the formulas are quite suitable for saltwater species. I have several institutions and hobbyists helping me develop some salt specific formulas and will relabel a few of the current formulas for salt.

    I didn't come on here to plug my foods but since you asked about them, I will take advantage of the opportunity :)

    Here are some videos a friend/dealer came up with introducing the line.

    [video=youtube;IXmZ4kWb3X4]https://www.youtube.com/watch?v=IXmZ4kWb3X4&list=PLby5yv00rWaUzedmKeoIgzVO aUMEwOn9h[/video]
  4. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Dude, you need to make that work for clownfish fry (at least, past the initial stages where they need live rotifers), you'll make a killing. That looks like a really good product.

    That last post got snagged by one of my spam filters, not sure why. Anyways...

    I have to say that you are probably correct - the comparison should be made the other way - cubed frozen food should be reduced to what you call DMB, not the other way around. That makes sense.

    So, what would one do? Take a cube of their food and freeze-dry it, or thaw and dehydrate it? Talk about a process that needs to be done when the wife it out of the house - whew!!

    As far as gauging the phosphorus content of the food - that's anyone's guess. I could list my mixture of food and ratios of each ingredient and could probably get pretty close. But I have to say that your take on a different protein to phosphate/phosphorus ratio making a huge difference is spot on. I ran out of one batch of DIY food at one point, then switched to a bag from a previous batch (which had more water content IMO) and the screen drastically changed colors (it went bright green), then when the next batch was done, the screen went much darker while I was feeding the same amount. Then I switched to a smaller feeding-based sized LED scrubber and the screen has stayed nice and green, but the tank GHA has picked up near the high-flow areas (partly due to switching from one scrubber to another, and a ramp-up time allowed algae to get a foothold). It took a few months to "dial in" the LED scrubber, there was also a flow issue (pump related).

    But anyways, I'm open to ideas about how to at least reduce frozen food to DMB
  5. Allen Repashy

    Allen Repashy New Member

    Actually it is pretty simple......

    Hikari lists 86% moisture for most of their frozen products. here is an example http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=13937

    Ocean nutrition lists 85% moisture for theirs.

    I use 85% for mine....

    So all you need to do is go to the freezer and weigh some of the cubes you have..... or get a friend or someone on here to do it...

    Weigh a dozen or so and get an average. maybe do this for ocean nutrition/hikari and see how close they are.....

    Then just take that average weight and multiply it by .15 and you have the DMB food weight of the cubes.

    We can round quite a bit and still be a WAY more accurate than the current guideline you are using....

    if a cube weighs 3 grams, then we can call that .5 grams of dry food.... so a "2 cube a day scrubber" would nicely convert to a 1 gram a day (DMB) scrubber

    Most frozen whole animal foods are 50-60% protein and 10-15%fat..... total phosphorous will vary but 1% is likely a good average.

    So to further quantify the guideline you could say something like "based on an average protein/fat/total phosphorous level of 50/10/1"

    This would at least establish a pretty good baseline.

    On another note, My "Spawn and Grow" formula is currently being used and tested for conditioning broodstock and raising saltwater fry of clowns and other species at the University of Florida Aquaculture Lab and by several hobbyist breeders. :)

    Send me a scrubber and I can do some controlled studies :)

  6. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    What about those of us that are feeding a DIY food? How would we establish a water weight percentage?
  7. Allen Repashy

    Allen Repashy New Member

    I have no clue how you make your foods, but if you want to spend the time, it is pretty easy to get a fairly good estimate of the water content in your DIY mix if you have a scale handy.

    1. Make up a batch of your food just the way you feed it, and weigh out a portion that weighs exactly 100 grams.

    2. Take that 100 grams and put it in a heat stable lightweight shallow dish or pan. You could even just bend something up out of aluminum foil.

    3. Put the food in the dish/pan and weigh it again so you have a total weight of the food and the container together.

    4. spread out the food in the pan so it is as shallow as possible.

    5. put it in the oven at around 120-140 degrees.

    6. Pull it out every hour and weigh the whole thing, comparing it to your original weight of the food and container combined. (it will start getting lighter)

    7. Do this once every hour, or half hour, until your weight isn't changing.

    8. Once it doesn't get lighter, you have evaporated off all the moisture, so you are left with a "dry" version of your mix.

    9. The amount of dry food you have left (not including the weight of the container), is equal to your dry weight percentage.. (if you have 25 grams left, then 25/100 = 25% solids and 75% water.....

    10. Repeat whole process to confirm!

    Of course the nutrient/phosphorous density of your mix is going to be something you will have to guesstimate based on your ingredients.

  8. Allen Repashy

    Allen Repashy New Member

    Nori is about 30% protein and low in fat, so a good rule of thumb might be that you could double the amount of nori you are feeding on a DMB compared to the DMB of whole animal feeds. (because they have twice the protein and fat) Nori (Porphyra sp.) is low in phosphorous, (follow link to Nori/Laver analysis) .....about .5% so this is also about half of what you would expect in whole animals.

    So I would say 1 gram or Nori would put a similar load on the system than 1/2 gram of whole animals (DMB)

    You would need to weigh out some sheets to tell people how many square inches insheets this is by volume.... but different sheets are different thicknesses, so again, everything should be weight based, not volume.
    Last edited: Dec 13, 2012
  9. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Sizing a scrubeer based on feed (guideline review)

    This same method could be applied to harvesting algae and measuring growth to determine filtration effectiveness. What would be interesting would be to know both and see if input = output.

    I have been in charge of the ingredients list for the last 3 batches of our DIY food. Off the top of my head, this is the list (I'll revise when I get home)

    - 22 lbs shrimp (before thaw & peel - we lose 25% weight from that)
    - 8 lb Cod filets
    - 6 lbs bay scallops (dry packed, no phosphate)
    - 4 lbs squid
    - 3 lbs baby octopus
    - 4 lbs krill (less water that it's frozen in)

    Frozen cubes (brine shrimp direct) each tray is 3.5 oz or 100g
    21 trays of mysis
    7 trays each of:
    - brine shrimp
    - spirulina enriched brine shrimp
    - bloodworms
    - Pacifica krill
    - Rotifers
    2x 1 kg flat packs of Daphnia

    1x 40 oz PE mysis (rinsed)
    1x 16oz Aqua Treasures mysis
    6 bars of a product a can't mention by name because they basically told me they could sue me and/or our club for claiming that I/we used their product without paying a royalty, even though it was basically free advertising (ok, off my soapbox now)

    Coral food & additives:
    1x 16 oz bottle Kent coral-vite
    1x 8 oz bottle Kent marine C
    2x 1 oz bottles Kent Garlic extreme
    2x 60 mL bottles Selcon
    2x 1.5 oz jars Reef chili
    1x 56g jar Coral Frenzy
    1x 30g jar TLF PhytoPlan
    1x 30g jar TLF ZoPlan
    1x 16 oz bottle TLF Marine Snow
    8 oz extremely puréed fresh market oysters
    1x 300g jar 1mm NLS pellets
    40 sheets of unroasted Nori (torn into pieces, added at last minute)

    I think that's it. Made close to 74 14oz bags.
    Last edited: Dec 13, 2012
  10. Allen Repashy

    Allen Repashy New Member

    Ok, So you are making a frozen food out of this? Anything you make into a slurry is going to be close to 85% moisture if not more (I see you are adding quite a few liquid products) so you shouldn't be far off of any other frozen food when you are done.

    Yes, you could use this method to compare input and output of the system.. but the growth of the animals/corals in your system is also going to be removing nutrients from the water column. Fish use nitrogen to grow and phosphorous to make bone for example. Your true measure of efficiency would have to be in a system where you are only adding food and letting bacteria do the rest.... but this wouldn't really have much more value than just checking your nitrate and phosphate levels in the water.
    Last edited: Dec 13, 2012
  11. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Sizing a scrubeer based on feed (guideline review)

    The only reason I thought it might be a lower % of water is that we mix this with a paint mixer bit on a heavy duty drill, and before adding the liquid supplements, this stuff does not mix at all easily. Next time we are going to use a paddle mixer but like what they use for drywall. One time we had to reach in and mix if by hand it was so thick. I'm not kidding, reaching into a 5g bucket and mixing by hand after adding the garlic is lets say not fun. LOL
  12. crashmushroom

    crashmushroom Member Customer

    Thats alot of food how long does it last floyd
  13. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    LOL that's not all just for me!! That was split up between over a dozen people. I took I think 8 bags and that is enough for my tank and the doc's tank for about 6 months.
  14. crashmushroom

    crashmushroom Member Customer

    Lol i was wondering :)
  15. acorral

    acorral Member Customer

    Just my 2c to the conversation here...

    Got the chance to freeze dry a very similar diy slurry food, 700 grams of frozen slurry turned into 50 grams of solids, that is around 92% moisture !!

    Not sure if pellets or flakes are as dry as this stuff is but I suspect it could be simillar...
    Peter likes this.
  16. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    Real-world confirmation is always good, thanks for posting that Andres, and welcome to the site!
  17. acorral

    acorral Member Customer

    Thank you Turbo !!

    Didn't knew about this site !! It's good to know there are still interesting and open discussions on the algae scrubbers area !

    Regarding the freeze dried food mentioned... I have noticed that it is indeed very concentrated in terms of N and P or at least that is my conclusión based on this: I can almost double the amount of spectrum pellets I feed the tank and barely notice it on increased algae growth but when I use this stuff it really pumps up the algae...

    I suppose they use some kind of fillers for pellets, fiber or something...
  18. Turbo

    Turbo Does not really look like Johnny Carson Staff Member Site Owner Multiple Units! Customer

    That wouldn't surprise me, good observation.

    So if frozen food reduces weight by 90%, and then still has 2x the nutrient power of pellets, then you could say that the equivalency ratio between frozen and pellet is more like 10g frozen is equivalent to 2g of pellets. (10g x 10% = 1g, 1g x 2 = 2g)

    If you use The "ocean nutrition" size cube (which is 2.5-3cc) for the cube rule, and assume that 1cc = 1g, then a 3g cube would equal 0.6g pellet, which is equal to 0.1 oz.

    Now let's go back to the rule:

    1 frozen cube per day (2-sided screen), or
    10 pinches of flake food per day (2-sided screen), or
    10 square inches (60 sq cm) of nori per day (2-sided screen), or
    0.1 dry ounce (2.8 grams) of pellet food per day (2-sided screen)

    So it would appear that this number was pulled right out of somewhere dark, because 2.8g / 0.6g = 4.67 or almost 5 times more than the amount a conservative analysis would give us.

    This get even worse if the basis size of the cube decreases to 1cc, now this 2.8g number is 15 times larger. But I believe the 3cc number is the correct number to go by, and this exercise supports that.
  19. acorral

    acorral Member Customer

    Have been thinking about this subject and got to this "conclusion"

    We know now that many factors are in play that really define the true capacity of a scrubber and those are not only screen size, light watts and flow... We know that other factors are equally important as spectrum, lumens instead of watts, disolved co2 in the water, ventilation of the screen chamber, submerged or not, waterfall or upflow, bubble count or volume, screen or other surfaces, strings or not, etc etc.

    The way we define the capacity of a scrubber doesn't necessarly has to be related to a "how to" or "diy guide"...

    Have tou ever seen a sizing guideline for skimmers? Reactors? We have general rules of thumb or best practices but their real capacity is not defined by any of that design factors.
  20. acorral

    acorral Member Customer

    I am thinking about making some guidelines based on what a scrubber can really do in the water of a "reef tank" or similar setup under controlled variables...

    For instances... Define the capacity of a scrubber based on the days it takes it to lower nitrate from 50 to undetectable on a 5 gallon volume of water...

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