Phosphate Media

Oh I think I see now (since you added that last sentence). It seemed like you meant that you were dosing nitrate for the denitrifying bacteria. So you are saying that the denitrifying bacteria are reducing all the nitrate, leaving none for the macroalgae. So you add an excess of NO3 to allow the macroalgae to grow, and thus consume more phosphate. That makes more sense now.

But can you still clarify how carbon dosing ties into this, and that point about CO2, carbon sources, and bacteria?

 

Sorry guys, I think this was the ultimate hijack!

 

Different organisms utilize nutrients different ways. Eukaryotes, such as plants and algae, tend to be "photoautotrophic", loosely speaking, this means they can synthesize organic nutrients, such as organic carbon, from inorganic nutrients, such as CO2, using light energy. So, for them, the ratio of carbon from food sources, isn't as important, as there is a constant influx of CO2 from the air (the level in the tank is determined by the atmospheric partial pressure of CO2 pCO2).

On the other hand, bacteria, such as denitrifying bacteria, need carbon in an organic form to begin with. So, for them the ratio of organic carbon, to nitrogen and phosphate, matters more. So, if we want our system to utilize algae driven nitrate and phosphate removal, such as macro algae, then we don't need to worry too much about the carbon (Although, we may because if it accumulates, it may drive bacteria, but we can sort of just blindly try to remove as much carbon as possible via protein skimming and GAC). However, if we want to rely more on bacteria for nitrate reduction, such as the use of live-rock, or sand beds, or biopellets etc... then the carbon matters more, as the bacteria may use up the carbon, preventing further uptake of nitrate and phosphate.

So, we can "cheat" by using media, such as GFO to remove phosphate and get around the nutrient ratios used by organisms, but if we want to remove phosphate naturally, we need to consider nitrate and carbon and the ratios of the three. Natural methods may be less expensive than media though, so, may be a good option, but then, you need to consider nutrient limitations, because, the more efficient the "natural" methods works, the more likely it is we will run into some nutrient limitation, preventing further removal of other nutrients.

 

LOL, yeah, I'm not helping, but for the op to decide to use macro algae, or BP or GFO etc.. then it helps to understand the limitations (unless the op is now thoroughly and utterly confused, which is also possible... - in that case, "sorry" LOL).

 

Hmm, I see what you are saying now. So plants and other photosynthetic organisms use CO2 (and water) to produce carbon sources (like sugars) and O2. Plants also utilize nitrates and phosphates. Denitrifying bacteria oxidize these carbon sources, using nitrate as the final electron acceptor, thus reducing it to atmospheric nitrogen. So plants and denitrifying bacteria compete for the nitrate. For people that have phosphate problems, they can bypass this by adding extra nitrate. Now there is there is less competition, and the macroalgae can thus take up more nitrate, and as a result, more phosphate. Additionally, if there is more denitrifying bacteria, then there must be more carbon for them to oxidize. If there is no carbon source to oxidize, then there are no electrons to donate to nitrate. This is very logical.

On the other hand, tell me what you think about this... If you dose nitrate, that means that plants will use more, meaning more carbohydrates will be synthesized. So if you dose nitrate, would you really need to dose carbon? The amount would clearly be altered.. It seems as though it would be extremely difficult to calculate the ratio of nitrate to carbon. Can you test for carbon?

 

Right. I couldn't say though with certainty. For a long time scientists knew that due to eutrophication, algae could wipe out reefs. It appeared the algae was toxic, but no one could figure out what the toxin was. Finally, they realized it was largely due to carbon realized from the algae was driving excess bacteria and driving excess surface associated bacteria, destabilizing symbiosis and even smothering the reefs.

I don't believe that all algae release carbon byproducts necessarily though, although a lot will find its way into the water due to predation and as algae cells die off. There was some research that looked at carbon release by specific algae. IIRC, for example, macro algae tended to release much less than say turf algae.

There seems to be some evidence that carbon is very critical to reefs health, probably much more so than nitrate or phosphate and like other nutrients, there is an ideal range (I think around 1ppm IIRC and there is evidence with heavy filtration, our tanks are lower than this...). We can't really test it though, at least not with hobby equipment, so, out of sight out of mind I guess.

 

Fortunately, most of us are able to successfully combat algae growth (well at least those who utilize the resources that we have available to us - like RO/DI units). The OP will also soon be algae free as well. Thus, we won't really run into this problem.

Now, with regards to your setup.. Can you get into the specifics a bit? How big is your tank? And what is your bioload like? How much nitrate do you dose? And I'm not sure if you said whether or not you are dosing carbon.

On another note, what is your reasoning for dosing silicates? Lol do you just like the look of diatoms or something? ;D

I am pretty interested in this, and your on your way to convincing me to try this out.. However, I see two potential issues.. First, I don't have a DSB, its 1-2 inches (the pistol shrimp makes piles). This does not provide a suitable habitat for anaerobic bacteria. Thus, it is unlikely that I will be able to rely on denitrifying bacteria to consume nitrates. Second, if I did this, I suppose it would result in me using less GFO, if any at all. So I am wondering how much phosphate the chaeto in my 30g sump can actually consume.. At this moment in time, it hasn't grown in a long, long time. Its alive and green, but not growing since I made the move to the 90g DT. My nitrates are 0 ppm - Note that this value was obtained from an API test kit. I know that API test kits are notably inaccurate, but I don't really need a precise value for this parameter (i.e. save money where you can).

 

Don't want to get too far off topic. PM sent

 

started using the brightwells phosphate-e after never being able to keep a stable low phosphate level. phosphate -e is doing it.
tried thrives liquid phosphate remover and noticed the fish breathing heavy after each time i added it. this reaction was observed 4 times the last time i had water waiting to do a water change. and into the trash the thrive product went. i've never seen this reaction with the brightwells product.
also when i first started using the liquid phosphate remover and was dosing it near my skimmer ( which is located in my sump) the tank would cloud. after doing some reading im now dosing into a filter sock, ( 100micron since i didnt have any smaller) the flow is about 200 -250 gph going threw this sock. and noticed no cloud in my tank doing this.
after dosing into the sock . i set up a dosing pump and have it dosing the phosphate-e 4 times a day in very small amounts. this seems to be working out really well. im dosing 4ml a day total of the product. and its keeping my phosphates at a steady .00 per hanna checker. i plan to lower my dose to try and get my reading at .03 to .05

i realize this answer is a little late, but i hope it helps a bit

 

thought i should when dosing manually 4ml to 5ml was dosed all at once. and didnt not see any negative reaction from my fish or corals from the brightwells product.
dosing small amounts threw the day only started after adding a dosing pump.

as m2434 says research this. there are other things you should know to look for, other possible issues. when i started to look further into the issue with the thrive. i found out that the chemical thats most likely in the thrive can cause oxygen depletion.
not sure why i never seen this same reaction from the fish in the brightwells product? since they do not tell you whats in it the products on either companys bottle. im just guessing at what was happening with the thrive which was being dosed at recommended dose.
why brightwells dosent cause fish to breath heavy when dosing at recommended dose????? i havent a clue!