SilicateFAQs

FAQs on Marine Water Quality involving Silicons

Silicate limitation does affect algal growth.

High Silica Reading 10/15/14
Hi!
<Tarrell>
Due to a lot of diatom growth, I bought a Hanna Silica handheld test. My reading was 34 ppm. Is this acceptable?
<Yes; a bit high, but aquarists should not "fear" diatoms. Not harmful>
What’s the range to target? How do I reduce silica from the tank?
<Mainly via regular water changes and gravel vacuuming, replacement with water with less [Si]>
I use RO/DI for my water changes and my TDS meter reads 0.
<Ah yes... the Si02 from your substrate/s likely>
Thanks.
Tarrell
<Welcome. Bob Fenner>

Diatom Issues! Silicate control in a well maintained system. 11/15/2009
Hi team!
<Hi Neil.>
I have a 180 litre Juwel Rio reef that has been setup for nearly 3.5 years, however, over the past 3-4 months I have had real issues with diatoms and hair algae like never before.
<OK>
My tank specs are as follows:
Tank: Jewel Rio 180 with internal filter chamber + powerhead
Dimensions: 101x41x50 cm (40x16x20')
Lighting: Arcadia Luminaire (4x 39W T5 2x Marine White + 2 x Actinic Blue) (tubes replaced 15-03-09) with 8hr photoperiod (2x 30 min blue only at start/end of day)
Water Disturbance: 2x Seio M620 + 1x Koralia 1 Powerheads
Skimmer: 1x Deltec MCE 300
Capacity: 180 litres (41gal/49 US gal) @ 24 degrees
Capacity with rock: 153 litres (33.7gal/40 US gal) (24-03-2007)
Rock: 30kg Fiji live rock
Substrate: 1' Coral Aragonite and Caribsea live sand (2:1) (27-06-2007 and 28-02-09)
Water: D-D Reverse Osmosis (4 pod) (Media replaced 14-06-2009) + Reef Crystals (560g /17litres per water change) = 1.024 S.G.
Chemical Filtration: Purigen, activated carbon and Rowaphos in filter chamber in tank (all replaced every 12 weeks (or if any detectable levels of compound found)
Nitrates: 0
Phosphates: 0
Carbonate Hardness: 8.6 dKH
<All looks good. Have you tested for silicates? One thing to keep in mind as well, a reading of 0 on a test kit does not mean that you system is not producing any of the compound in question. It simply means that what is being produced is used up.>
Water changes are performed weekly with 17 litres of RO water at same SG/temp and have been aerated for 48 hours before use and the only livestock I have in there is a cleaner shrimp and banded serpent starfish - along with numerous red legged hermits and snails. All corals appear in fine fettle with polyp extension good and no tissue degradation/signs of atrophy etc.
<OK>
I have recently started to treat with a single ampoule of both Bioptim and Biodigest after a water change at the advice of my LFS and am not seeing much difference. 8 weeks in and not much has changed.
<Personally, I am skeptical of such additives, and they are no substitute for good practice.>
I appreciate the best way to combat diatoms is a) prevention of introduction and nutrient export, however, with a reading of 0 ppm from my RO water (untreated tap water is 320 ppm) and the skimmer pulling off a small amount of dark skimmate per day, I am not sure what else I can try/what I am doing wrong -- I have even checked my top-up / water change buckets are of food grade quality and are rinsed after each use!
<One if the biggest single contributors to diatoms is silicate, which is normally introduced by adding sand or disturbing an existing DSB.
Of interest I used to have a 3' DSB which was removed (again at the advice of the LFS) when the issue arose -- I had added extra aragonite sand prior to that as I thought it had slowly been degraded as I have read DSBs are prone to do.
<This is likely the culprit. Adding and removing sand caused the silicate levels to rise, causing the diatom bloom. Similar with the hair algae and nitrate and phosphate. Personally, I would have left the DSB in place.>
As you can see I take my maintenance schedule very seriously and am not knee-jerking at changes seen in my tank --

I'd been avidly reading WWM for a good 5 years and appreciate all of the school-boy errors that can be made and have only called in the favour of this 1-1 help once before (generally things are covered so well in the FAQs)!
<If they are available in your area, I would look into a silicate test kit. Test your tank water, test your makeup water, and test the water before and after the RO system. I would suspect that you have an excess in your tank. Also of note, silicates may not necessarily be removed with RO The only way I am aware of to remove them completely is with De-ionization. The good news is that it will pass in time as the silicates are used up. Until then, I would keep up with the water changes, perhaps making larger changes every week.>
Thanks for reading.
<My pleasure.>
Neil
<MikeV>

Calcium supplement question... culture, keeping Nephtheids 6/12/08 Hello <Howsit?> I have a 500 gallon total system for non photosynthetic organisms and have been working with Dendronephthya and Scleronephthya for some years. (I published an article on Reef Central under Dendronephthya Husbandry a few months ago about my friend Chuck Stottlemire's tank). The trouble is, Chuck's tank has done VERY well with these organisms; mine hasn't. (The trick seems to have been continuous feeding of phytoplankton and rotifer product). <Necessary... in particular, a mix of "right sized" organisms> My organisms slowly die like everyone else's. For years I have supplemented to NSW values with silica. I haven't checked the alkalinity or calcium for years, since there was little calcification/ coralline growth. <Mmm... these materials still get "used up" in captive settings> I fussed with phosphate issues, which I suspected was the problem (up to 2ppm); when I lowered the phosphate with vodka I would get initially better expansion then things worsened... <Ethanol is not a long term solution...> Long story short, I checked alkalinity and found it to be 26 DKH, calcium 280. Hmmm... no alkalinity additives for years, weekly 10% water changes with moderately hard water. After staying up half through the night trying to figure this out, I think I found the problem- chronic silica additions add alkalinity, just as nitrate additions would. (I have supplemented nitrate as well when the macroalgae shriveled with undetectable nitrate). This presumably forced the calcium down. <A mis-balance all the way around> After one large jar of calcium chloride, <... not a good idea> I got impatient and bought a calcium supplement from the pool industry; <Ditto!> I read the chemical spec sheet, and it contained 98% calcium chloride, 1% strontium chloride, and a little magnesium, no other additives. I've been spooning this stuff in. Over one week, the calcium rose to 380, the alkalinity then started to fall now in the range of 16 DKH. <You tell me what I know> I have read somewhere that some of the soft corals prefer a NSW DKH of 8-12 for optimum polyp extension, which is where I want to go. <Okay...> Needless to say, Nephtheids look terrible. However, sponges, snails, fish all look fine. Question: 1) Do you agree the silica was the cause? (Actually, my stupidity is the proximate cause, but is the silica the mediating factor?) <Only one of a few listed and not> 2) Is the pool industry additive safe? <Not really> 3) Am I going to have to ultimately add so much chloride that the whole system is poisonous and massive water changes are needed? <This would happen in time, but likely other factors will cause you to give up first> 4) If water changes, I was thinking of continuous water changes of 1000 gallons over a week or so via doser/exchanger. This would still leave about 30% or the original water in the system. Is this enough? <Likely so... I would be reading... perhaps a few good tomes on general marine aquarium water chemistry. I would (categorically) NOT use calcium chloride as a long-term, habitual supplement, NOT use C2H5OH either, NOT supplement Si02... for a system of this size, type I WOULD look into a calcium reactor, and a very large refugium and DSB and the culture (likely separately of nano, pico-plankton et al. sizes) if your intention is to sustain Nephtheids. Bob Fenner> Thanks as always Charles Matthews M.D.

Re: calcium supplement question... and Silicon... 6/12/08 Bob, thanks for the thoughtful reply. To clarify, I wasn't considering using calcium chloride long term, but to bring up calcium until I could restart a balanced supplement (rather than do a 1000 gallon water change). <Understood> My reading (I suspect I've read anything you might suggest- I particularly follow Holmes-Farley) suggests this would be a standard approach first as a temporary measure, <We don't differ often, but this is one case. I taught H.S. Chemistry and Physics... and have spent many hours trying to formulate, practice if you will on my fellow aquarists, just how to "make known what needs"... Am very sure that you have similar sensibility in your dealings as a doctor of medicine... I assure you my short statements here (and I guess most everywhere) are borne of much experience and background/related knowledge. I would go so far as to state that I would in most all cases never supplement with calcium chloride... for a few reasons... again, these are archived on WWM, in articles and books by me...> since this imbalance wouldn't be corrected by just adding a calcium reactor or other balanced product (at least on any reasonable time scale for water changes). <Correct... I would execute at least one massive water change here... hundreds of gallons...> Are you thinking that I would have been better in this particular system (rather in a general say SPS system) by not correcting the imbalance first at all, and just going with my 10% weekly water changes? Or just proceeding to changing 1000 gallons or so first? <I'd change a large percentage... If you can/could, all of it> Also, the silica additions were Holmes-Farley inspired, <Again... we disagree. Silicate is not a rate-limiting material for what most all hobbyists want to do... I take it you are purposely/trying to culture diatoms/bacillariophyceans> and I thought it was interesting that this seemed to be the problem, and I've not seen this discussed before by him or any others. The addition of nitrate alone, such as for a planted tank, will raise alkalinity during conversion to N2,, <Only temporarily> and I presumed that the same change occurs with silica; <Almost w/ no measure... are you administering some form of silicon dioxide? This has a very low solubility in water> this was the cause over time for the reason calcium and alkalinity became skewed. <Mmm, I am dubious to the extreme> Silica depletes over a few days in my system with improved diatom growth and benthic grazers, so I was happy about this; silica additions have been discussed by Delbeek and Sprung in vol.. 3 as well... Adding silica, I think would increase alkalinity over time when NSW values are maintained by additions; <How?> if however you add silica to a diatom culture, and then add the diatoms strained of culture water, I wouldn't expect the same alkalinity problem. So, although some authors have been suggesting adding silica in this context to stimulate diatom growth, the problem of gradually increasing alkalinity will been to be monitored, and would need calcium supplementation to maintain balance. <Yes... these values are more important than silica/te/Silicon concentration> This makes the whole approach of adding silica to the tank problematic because of the increased chloride. <? You're adding a salt of Si2? Tetrachloride? So much that you believe there is size-able introduction of excess chloride?> Adding a silica based mud refugium, or silica sand, might be a better option if stimulating diatom growth in aquaculture is desired. Do you think I've got the silica problem understood now? <Again... I am not a fan of supplementing Silicon in any format... in specialty cases (perhaps as yours) where you want more of what this will get you (e.g. Diatoms), as you state, it is best to culture these elsewhere, rinse the medium before introduction into another system> Thanks as always <Welcome. BobF> Re: calcium supplement question... Now just Silicon 6/12/08 I was using the Holmes-Farley recipe of "water glass" silica, 12 drops whisked into a quart of cold water and poured into the sump once daily. <Have just re-read RHF pc. on: http://www.advancedaquarist.com/issues/jan2003/feature.htm The amount you've been adding is miniscule...> This maintained silical levels NSW by Salifert test kit, then declined to undetectable over a few days if stopped. <Yes... soluble silicates can/do fall by about 50% a day in most settings...> The mechanism I was postulating- and I haven't seen this discussed- would be that the silica and the nitrate charges are similar. The mechanism would be the same as if you added nitrate regularly. <Mmm, chemically perhaps, but not biochemically... depending on what is "going on" in a given system, NO3 can be rapidly converted/absorbed-incorporated or not.> As I understand it, during the ammonia catabolism cycle, the conversion of nitrite to nitrate is an acidifying reaction; <Yes... aerobic nitrification is reductive... results in acidification> the conversion of nitrate to nitrogen gas restores that alkalinity. <Can... but this actual balance (anaerobic to hypoxic) is rare as hen's teeth in captive marine systems> If you skipped the nitrate-nitrogen step and just added nitrate alone, that would produce increase in alkalinity long term. <Mmm, no... much more going on here... try this and see... and we can speculate re some major reaction series re> Along the same lines, an imbalance with decline in alkalinity as opposed to a balanced decline, will occur due to water changes that export nitrate. <Among other contributing influences... overall respiration, metabolism, deamination period... drives down pH, nicks away at alkaline reserve> I presume the conversion of silica to biological forms of silica is an alkalinizing reaction similar to the conversion of nitrate to N2. What you think, Bob? (smiley emoticon!). <Keep on keeping on Charles. BobF>

Re: calcium supplement question Bob- the ion that goes with the silicate is sodium (sodium silicate). 6/12/08 <Mmm, yes... in this supplementation scheme> I am presuming that the silicate charge is like the nitrate charge after dissociation. <I don't know if I'm following you here... the valence charge of each dissociated molecular species as ions? Silicon, like carbon, can share up to 4 electrons per atom... can/does exist in different valence states depending on local chemistry... As a very common element (makes up more than a quarter of this planet's crust) Silicon rarely exists in elemental form... the same is the case in our aquariums... I do want to emphasize to any browsers to CAREFULLY read RHF's article/s re sodium silicate use... this material is very caustic (alkaline). BobF>

<<Is the issue here one of whether folks should supplement (somehow) with Silicon... for the purpose/s of promoting Diatom et al. growth (many organism groups use, are rate-limited in captive systems by a lack of...) to the possible exclusion of "pest" green et al. algal growth? Each must decide for themselves, but I am of the opinion that such supplementation should only be done with sufficient knowledge and great care... as there are a few important downsides to such practice. RMF>>

Skimmer and Silicates 01/23/2008 Aloha Bob and Crew, <<Hello, Andrew here>> Does a protein skimmer remove silicates from a marine aquarium? Eric <<A protein skimmer won't effectively remove silicates from the aquarium. Theses need to be removed by the use of a removal media such as Rowa-phos. You can limit the amount of silicates in the tank by using zero TDS RO or RO/DI>> <<Thanks for the question. A Nixon>>

I have a serious Silicate problem. Silicate problem - 07/25/07 OK, here goes.... <Shoot> New tank Nano 12 Gallon AP. You have dealt with me before and all was going well. I have the chiller hooked up to the AP if you remember my photos a few days ago. All my parameters could not be better. I was actually surprised myself. All of a sudden I started to get a little diatom outbreak. Again the tank is only like 6 days old so it is expected to some degree. <It's not unusual at all.> However, I have been keeping the white lights on longer each day until today which brought it to 8. Meanwhile, the actinic have been on every day for 10 hours. You get the idea. I was kind of curious why I had a diatom outbreak when my phosphates were 0 and all my other parameters were basically where they needed to be. <A fresh tank with nothing established giving them some competition. Happens in most new systems.> Ammonia - 0 ; Nitrites - 0 ; Nitrates - 0 ; Phosphates - 0 ; Mg - 1200 (needs to go up a little ); Ca - 480; DKH - 12 (needs to come down a little ); PH - 8.3; SG - 1.023 So.... I decided to go to the store and get a Silicates test kit. Brought it home and tested. Let's just say that the color chart on the Red Sea test kit goes up to green. My color was Dark Blue. I am off the damn chart I exclaimed. Amongst a few other things. I took such care in making sure that I was not going to have problems with silicates this time. I use DISTILLED WATER (tested no silicates) <okay.> I use Via Aqua OceanPure Sea Salt (tested in water no silicates ) <okay> I use CaribSea Aragonite Sand (testing in water with salt and sand no silicates ) <Did you rinse the substrate? If not did you test the dust with water and salt?> I even left it to leech for 13 hours at 1.024 and 78 degrees with a pump and tested all those scenarios again. No Silicates.... <okay> There is nothing else in this tank except for the Live Rock ( hmmmmmmmmmm) I am currently in the process of having a piece of the rock in 16 ounces of water, salt and sand and I am going to test this out tomorrow. I purchased my CURED rock from Pacific East and to tell you the truth I could not have been happier with it when I got it. It really looks great in the tank. However, this is the ONLY item left that could be the problem and now I am not so happy with it. Again, there is nothing in the tank, no corals, no fish, nothing except the LR, Sand, Salt and Distilled water. So now where am I. Hmmmm... Did a 5 gallon water change. Tested.. Looks a little lighter in color, but it's still freaking blue. I really don't know where to go from here. Called Seachem Phosguard as per Seachem I should use the 100ml package for a week and see where I am at. Continue use until I get it at least on to the test kit chart and then maybe it will be over.. OR? <Can use that if you want, but be careful not to over treat.> I think this is where I need some suggestions from you. To go through everything I did. http://www.njreefers.org/joomla/index.php?option=com_smf&Itemid=26&topic=3223.0 and to end up with the worst silicates ever in history just stinks. Advice, Suggestions??? <Time will likely solve the diatom problem. The two major sources of silicates in tanks are: used water and dust of the substrate. If you can rule out both, I suggest the silicate comes from decaying sponges (some have silicate spicules). You can remove the sponges as a silicate source to help with your current problem, but I'd prefer to keep them and see if they grow again when the tank matures. In your case I'd simply siphon out the diatoms (which are now binding the silicates) several times and dilute the dissolved silicates with larger water changes with your silicate free water and salt. The system is small, so this should be no problem. Rinsing the mechanical filter parts will also help to remove diatoms and consequently silicates from the system. Patience and consistency will help here. You silicate remover possibly will fasten the silicate decrease.> Kind regards and as always a big thanks for your help, Stephen <You are welcome. Marco.>

- Phosphates and Silicates - hey Mr. Fenner. <Mr. Fenner is in Chicago, attending IMAC. JasonC here in his stead.> mike here, I was looking on the site and notice there isn't much info on phosphate levels and silicates. my reef tank has been up for about 2 years now and I've managed to keep things looking good up till now without worrying about phosphates or silicates. (I only keep track of calcium and alkalinity). I've read some articles on how important it is to keep phosphate levels low so I've decided to invest in some test kits and phosphate remover products. any recommendations on which brands. <I've been told that Rowaphos is the best product out there, but I'm sure there are several that do a fine job.> a friend of mines recommended iron based and not aluminum based products for whatever reasons. could you fill me in on some basic phosphate and silicate info? <Start reading here: http://www.wetwebmedia.com/po4faqs.htm and here http://www.wetwebmedia.com/silicatefaqs.htm > links to pages are cool also. thanks Mr. Fenner. mike <Cheers, J -- >

Silica, Kold Ster-il, Alumina, DI & RO 3/7/05 Dear Sir or Madam, I'd like to solicit your recommendations for silica removal from tap water that contains 10 ppm of silica with a pH of 8. <I guess my first question is "why is this a priority?". Excessive diatom growth can often be controlled with herbivorous snails and the snail fecal pellets make the nutrients better available for export via as skimmer. Starving the diatoms of silica (almost impossible) would likely leave other nutrients more available to other algae that may be more difficult to control.> The Kold Ster-il System I've installed does not appear to remove silica. According to the Salifert test kit, both my tap water and the outflow of the Kold system contain ~10 ppm of silica. Poly-Bio-Marine, the maker of the Kold Ster-il System recommends the addition of their activated alumina media plus a deionization (DI) stage. <IMO, these steps would defeat the purpose of using the Kold Ster-il by removing all of the "good stuff" like calcium and carbonate.> I am reluctant to use alumina because I do not know of an affordable test kit that can verify the recommended potable water standard of less than 0.05 ppm of aluminum. <Any such kit would probably be prohibitively expensive.> I am also reluctant to use rechargeable deionization media because silica must be removed by the anion stage at high pH. This is impossible because the anion stage usually follows the cation stage that lowers pH. <A single stage DI unit will be a mixed bed unit, and will not solve this problem.> Is there any reason why the anion stage cannot come before the cation stage? Since the outflow of the Kold Ster-il System is ~8, the anion media should be more effective at removing silica at that pH. However, I do notice that deionization systems with an anion 1st stage use a mixed-bed 2nd stage instead of a cation 2nd stage. Why is that? <The order of the stages has to do with the fact that one of the resins can be damaged by the high or low pH generated by the other. I suspect that the pH neutralizing effect of using a mixed bed when the anion bed is first helps ameliorate this problem.> Rather than use a non-rechargeable mixed-bed DI system, perhaps I should throw in the towel and obtain a reverse-osmosis system? <If you are still convinced that you need to eliminate the silica, this may be your best bet. Several companies that market to the aquarium industry now market units especially designed to remove silica.> What should be the target silica level in water for use in hydrating marine salt and what technology should I use to reach that target? <In my personal opinion, there is no reason to worry about silica, except in some exceptional cases. See here: http://www.advancedaquarist.com/issues/jan2003/feature.htm for a lot more info as well as to read about a guy who actually supplements silica!> I would appreciate your recommendations. Thanks very much. Regards, Paul. <Hope this helps! AdamC>

- Filtering out Silica - Hi folks, I asked a question back on March 29 and never got a reply. I'm still floundering with the issue, so have combined my original email, updated, with a follow-up. <Ok.> My well water has silica reading of 2 ppm <That doesn't sound like very much - two parts per million...> My tank has been setup for 4 weeks and I have a lot of algae, even with very little light on during the live rock curing process (which is now complete). <This is very normal for new tanks, and I doubt the silica is the catalyst here...> The local dealer, as well as your webpage and others, all recommend I get an RO unit to solve this. Problem is, our well is iffy at best for volume and we have to be careful, especially during summertime, to conserve water. I'm worried that the RO unit will waste more water than we can spare. <Then store the waste water... this is still clean stuff and more than adequate for cooking/drinking.> There is also a space issue--fitting the tank and it's spare salt holding tank in was no easy matter, I have no idea where I'd put another holding tank for RO water. Here is my setup: 75 gallon tank, 14 gallon refugium, 6 gallons in sump, 110 lbs live rock, deep sand bed lighting is power compact fluorescent on main tank skimmer refugium with macro algae, a few inches sand, and lighting on reverse photoperiod pump is Mag Drive 18. I do add Marc Weiss Coral Vital per directions (currently, daily) Water change 10% weekly test readings: phosphate .06 (too high, but PhosGuard should help this) nitrite 0 nitrate 1.5 ph 8.2 alk 3.5 meg/L silica 2ppm Is there any macro algae I could put in refugium that would be especially good at removing silica? <None of which I am aware.> I am currently trying Phosguard, which is supposed to help silica also (too soon to tell if it is working). Do you think that (or some other product you know of) can take care of my silica problem without RO/DI? <You haven't convinced me yet that you actually have a silica problem.> If there is no way out of RO/DI, do you know which brands might be more efficient and waste less water? <All are roughly the same.> I estimate I would need only 3 gallons a day to do top off (1.5 gallons a day) and 10% water change a week. I have read that DI is really what matters for silica, not the RO. Is this true? And if true, does any company make just a DI unit? <Not off the top of my head, but one could be assembled from parts readily available at any Home Depot.> Thank you very much! <Cheers, J -- >

Placement of probe to measure ORP Thanks for the earlier help, I've got a strange question that I can't seem to find an answer to anywhere. <Okay> A few weeks ago I started to get a diatom bloom in the aquarium. On the glass, coating the sand, etc. I purchased a silica test kit to see if I could track down the source of the silicate, and some PhosGuard (Seachem) to get rid of what was in the tank. Well, the readings in the tank are going down (started at 2 ppm -- per Red Sea Silica Test), current reading is about .75 ppm. <So far, so good. Very many systems have initial cyclical diatom scum outbreaks...> I've traced the source of the silica to my top-off/change water which is supplied by a 4-stage RO/DI filter. When I tested the tap water the silica reading is off the chart. According to the local water company quality reports I should expect to see 8.7 to 12 ppm at the tap. <Yowzah!> Once the water has been through the RO (but not the DI) I see a drop, but it's still above 1ppm. Post-DI doesn't seem to be a difference. <Shouldn't... the silica, likely as silicate is not ionic... it's not a charged (as in valence) chemical species. Take a look on the Net re what deionization is/does... perhaps a H.S. or college level chemistry text.> The strange part is that I have a TDS meter that measures both the water going into the RO (usually reading 24-32 ppm) and coming out of the RO (always 0 ppm). Granted, the meter is reading anything in the water, but isn't zero = zero? <Something is awry here... total dissolved solids includes silicates> In a nutshell, I'm confused as to how to get the last of the silica out of the water supply, or if I should just deal with it through regular use of PhosGuard. <You are possibly "overthinking" the situation here... If it were me/my system/responsibility I would either simply ignore the small amount of resulting silica OR look to have it "taken up" in the living processes of the life in your system. Get some live rock, purposeful algae going (perhaps in a living sump/refugium) and you will quickly find there is no "silica problem" and no need to use chemical filtrants> I've provided links to the products referenced in case it helps. Thanks in advance. Sean Silica Test ( http://www.marinedepot.com/md_viewItem.asp?idProduct=RS3129) PhosGuard ( http://www.marinedepot.com/md_viewItem.asp?idProduct=SC3259) Water Filter ( http://www.aquariumwaterfilters.com/RODI/Barracuda.html) <Much appreciated. Sean, do you understand the concepts of "cycling" and "nutrient availability"? There is nothing wrong with having some silicate, some diatom smears at first... these too shall pass. Bob Fenner>

- Silicate Questions - Dear Wet Web, I have a silicate problem. I run my tap water through a HI-S unit (no DI) and it drops the silicates in my tap from the highest on my test kit (at least a 2) down to around 0.2 . The tank is a 125 and is currently not running, but when I do start it I was planning on having algae (probably Caulerpa) in the sump. I know these compete with slime algae for Phosphate, but will they use silicates and be good competitors for Diatoms? <No.> If not are there any macro algaes or other organisms I could use that would be good competitors for diatoms? <Not that I am aware of... plan on using some of the typical methodologies for keeping BGA under control, like brisk, random circulation/flow and underfeeding.> I am currently planning on using phos-guard until I get a chance to add some macro-algaes, because phos-guard is so expensive. Thanks for all your help Emmett <Cheers, J -- >

Silica and the use of it in aquariums II 11/7/03 But the article does talk about diatoms and silica sands, and says that there is no obvious diatoms inhibitor shall we say in using silica over aragonite sands. And that is exactly what I wanted to get your input on!. I am not commenting on the anecdotal concerns of silica sand as a source of elemental silica for the growth of diatoms (composed of silica), but rather that the structural shape of the grains (angular versus oolitic) is the reason for algae like diatoms to settle faster (more conducive on sharp sand)> So is it or is it not (silica) a diatoms conductor? <I believe the question is moot... neither. I say this because any minor favor of grain size to diatom growth is minutia compared to the much bigger issues of nutrient control in an organically rich aquarium. Again, it is moot because your/our aquarium husbandry including nutrient export processes (skimming, water changes, carbon/ozone, etc) should be easily good enough to handle any small disadvantage or not to using silica sand. I cannot be any clearer than that, mate. Use silica sand confidently if you like. Most folks will benefit from the more natural media of aragonite instead (shape and composition, buffering ability, etc)> thank you Mohammed <wishing you the best. Anthony>

Silicate Situation... Hi Purified-H2O Guru: <Well, I consider myself more of a high silicate source water victim! LOL...Scott F. at the keyboard tonight!> I really don't want to RO my tap water as it is pristine, above 8.0 straight out of the tap, and full of hardness (good for marine tanks, bad for everything else.) <No discus for you...> No copper, lead, iron or other nasties ... even chlorine is so low it's almost usable without Amquel-nuking. But, silicates are around 70 ppm...which may or may not be fueling diatom blooms in my tank. <Yep- they are! I know whereof I speak on that one!> I have 2 questions : a.) Isn't natural sea water around 2000 ppm of silicates (or of silicon specifically), and therefore adding 70ppm is only increasing this load by about 3.5% ? <Mathematically correct...But in a closed system- silicates from source water can spell a nasty diatom plague...RO/DI is the way to go, my friend....Preferably, a unit with an extra silicate membrane...> b.) Is there a product that will remove just silicates and leave everything else alone? <Well, there are silicate "removing" products and resins, but they are both expensive to use on a continuous basis, and unreliable. Really a better move to go RO/DI with a good unit, like a Kent Marine "Hi S" model, or a SpectraPure 5 stage unit...Initial investment is high, but they pay for themselves down the line in terms of media replacements and frustration! Good luck! Regards, Scott F> Thanks, SLC

- Silica in Tap H2O - <Greetings, JasonC here...> Thanks so much for the wealth of info you all put out to all of us reefers!!! I appreciate it greatly tho I can easily get overloaded and overwhelmed by it all. My question concerns the level of total silica ( 9.6ppm as of Jan 03) in my well water, will it be problematic to my salt water aquarium? <For just silicates - between nine and ten parts per million is not very many...> I have since installed a DI system with a silica removal cartridge but am finding it does not last long before it needs to be replaced or recharged. <Yeah... you would likely benefit from some pre-filtration to that DI cartridge... would lengthen its life. Most commercial RO systems have at least two levels of filtration before the RO membrane and the RO before the DI if that is a part of the unit.> I think RO will be overkill and hoped the DI would suffice. <Perhaps not.> Maybe I do not even need to be concerned and can use it straight from the tap? <Also worth investigating, but you might also want to see what else is in your water...> I was also concerned with the lack of Ca and Alk in my RO and or DI water I use for evap top-off and was told by the LFS if the RO/DI water sits with aragonite gravel it will increase the buffering capacity and help with Ca etc. <I'm not sure I agree... that water would have to sit in contact with aragonite for a very long time... better to just add powdered buffers to the top off water.> My Ca of this method tested at 20ppm. My miniscule understanding of Ca reactors is that they use a low pH to release the Ca, my RO/DI does not have a low pH so might go so far as to guess this recommendation from the LFS is not true? <Calcium reactors use CO2 to produce carbonic acid which dissolves the media, creating calcium carbonate. This mix is circulated vigorously in the reactor to being as much C02 and water in contact with the media as possible. Very different from having water sit still in a container of aragonite.> I believe I read later that the 2 part Bionic is a good additive to keep these levels up? <It works, less complicated than setting up a reactor, but in time you will spend as much on two-part systems as you would on a reactor.> Thanks so much! Denise Goodheart <Cheers, J -- >

Phosphate/Silicate Good evening all, <Howdy Kevin, Don here tonight> Quickie, Marc Weiss Phosphate and silicate magnet. Garbage or useful? Harmful? 30 gal reef tank with softies. Worried sponge material will affect iodine and other trace elements. are a problem with a proper test kit and then find the source, not treat the symptom> Kevin RE: Phosphate/Silicate True and thanks for quick response, am setting up refugium in about three weeks, do you think this product is safe (ish) until then? think my seafood puree is the culprit despite rinsing first and only feeding what they will eat once a day. PO2 is only at .5 <still too high, so I see your concern> but is consistent and have tested the test. <Always wise to get a second opinion on the tests. Again, I would not use the Weiss product. While I have not needed it myself, lots of good remarks for SeaChem PhosGuard on the WWM forum at http://www.wetwebfotos.com/talk. Kudos on the refuge, excellent addition, keep in touch, Don>

Silicates Bob: <Gage here this evening, fresh off of a water change.> In one of your previous answers to a silicate questions, you state that silicates are absorbed by more algaes than just diatoms. Can silicates feed Green Hair algae as well? <they can indeed> I have a 75 gallon reef tank, here are some facts: 440watts VHO 50% 10,000k and 50% Actinic 10 hour photoperiod (all lights on) Mag Drive seven and sea swirl for return 3 maxi jet 600's with Tsunami Wave Timer sand bed is approximately 2.5 inches deep. 0 p04 0 nitrates Calc: 410 Alk 10 dKH ph: 8.2 Kent 24gpd TFC RO (well water) Tank is almost three years old. Just recently tested tap water for silicates, registered an amazing 21meg/l, ouch, that's really high. Could this be my problem with hair algae that has plagued me for over a year! <Yup, also could be related to feeding, fish load and lack of skimming?> I've got a hi-s membrane coming in the mail. I sure hope this takes care of the problem, any ideas? <Should help but may not fix the problem entirely. Maybe a new source of water, RO, DI, RODI? -Gage>

Silicate Hi Bob and experts, <cheers> Today I got few questions, 1) Is there any algae that absorb silicate other than diatom ? <tons... literally metric tons :)> 2) Other then using skimmer, PolyFilter, and RO , is there any other natural way to remove diatom ? <many natural processes do and can be harnessed in system dynamics like mass-harvested refugiums... still, its like reinventing the wheel. Why bother when the most direct and reliable way is to screen it on the import side with purified water used for evap and water changes and then aggressive skimming in the system? Both are key ingredients to success with marine aquaria. buffered DI water and a good skimmer that produces dark skimmate every day. Best regards> Thanks Regards Danny

RO Silicate Removal hello to all. I just have a quick question regarding silicates. do r/o units remove silicates, I am using one and it removes phosphates but what about silicates. I have heard several opinions some saying they do others say they don't. I cant seem to find any test equip to test for them. I want to remove any chance of having diatom outbreaks (hate them). if r/o units don't remove them is there any good products that do. thanks very much, love the site but couldn't really get an answer to my question so I thought I would ask. <Some units do, some don't. It depends on the membrane/brand. Deionization units will remove silicate. -Steven Pro>

Questions: Silicate removal, tapwater treatment Hi Anthony, <Good morning, my friend> Thanks for the fast response. This is a follow up of the questions that I asked earlier: I keep feather and grape Caulerpa. Will they absorb silicates? <not at all to the extent that I suspect you. like most folks, will desire. More so, they will exude far many more noxious compounds that at best inhibit water clarity as bad or worse than any other biological byproduct of aquariology...and at worst literally inhibit the growth of some corals (not all, of course...some species are better adapted and seemingly unphased)> Regarding the control inflow source water with chemical media if necessary... What do you think of the tap water purifier by Aquarium Pharmaceutical Inc? <I think it is the long way around the barn, so to speak. For what you are likely to spend on replacement cartridges in less than two years, you can easily afford a rechargeable two column de-ionizer that is a more responsible choice that also saves you money (like the KATI/ANI brand units). Quite frankly, I resent the mixed bed resin products that deliberately make it inconvenient for an aquarist to reuse an entirely rechargeable and renewable resource (the resin if it were separated as Cation and Anion instead of mixed in cartridges as they often are). It seems like an ironic waste in an industry that is founded on empathy and admiration for the natural environment. Anthony Calfo>

Question re silicates, removal <Greetings, Charles - JasonC here, how can I help?> Hello, I've bought some Coralife silicate remover last week because i have diatoms and i was wandering how much time I'm suppose to let the product in my canister filter. They specify on box to let it in 2-3 month but only when the level of silicate is low. They aren't specify how much time is the level is high. Mine he is so do i have to let it in like almost every remover product, 8 to 48 hours or what... <gosh, I'm really not familiar with the product, but based on your description, it sounds like the longer you leave it in, the better it will work. If one must leave it in for two to three months for a low load, then you'd have to leave it in even longer for a heavy load. To be quite honest, I'm not a huge fan of products like these and am quite skeptical as to their effectiveness.> Anyways, i hope u will write me as soon as u can because i very tired of those diatoms. <silicates, which give rise to the diatoms, are probably best addressed by using Reverse Osmosis [RO] water to mix your salt with. This way they are removed long before they get a chance to get into your tank.> Thanks for your concern.

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