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Biofilm In Planted Tanks — How to (Finally) Solve and Prevent Biofilm

How to (Final­ly) Solve and Pre­vent Biofilm

Issue 003/ August 23, 2020
if you just want to elim­i­nate biofilm (and keep it from com­ing back), here are the exact steps to solve biofilm in your plant­ed tank once and for all.

Biofilm is a com­mon issue to plant­ed tanks — I’ve seen the issue in my own tanks, as well as oth­ers’ aquariums.

In fact, for this arti­cle I’ve actu­al­ly inten­tion­al­ly caused a heavy biofilm in one of my own tanks—just to show how these steps work.

So if you just want to elim­i­nate it (and keep it from com­ing back), here are the exact steps to solve biofilm in your plant­ed tank once and for all.

Let’s get started.

Step 1: Under­stand What It Actu­al­ly Is

Here’s the deal: there’s a lot of con­fu­sion about what’s in biofilm. Here’s the tech­ni­cal definition:

What is Biofilm?

Gen­er­al­ly speak­ing, biofilm is the car­bo­hy­drates and lipids from organ­ic waste pro­duced in a plant­ed tank. The film’ is pro­duced by bac­te­ria feed­ing on the excess organ­ic waste present in the water — and that organ­ic waste can come from live­stock and plant life in the tank.

In reg­u­lar-peo­ple terms, that means biofilm stems from organ­ic waste — the stuff’ that’s giv­en off by fish and plants. Unless you want to remove all the fish and plants from your tank, we can’t elim­i­nate the source of the organ­ic waste.

But we can mit­i­gate the effects of that organ­ic waste:

Step 2: Pre­vent Biofilm Buildup

Biofilm only forms when organ­ic waste builds up past back­ground” lev­els. If you pre­vent it from ever reach­ing that point, it’ll nev­er form that thick sur­face lay­er in your tank.

The most effec­tive (and eas­i­est) method of pre­vent­ing biofilm buildup is using a sur­face skimmer.

Skim­mers used to be a salt­wa­ter-only” item, but in the past decade the indus­try has learned that the biofilm buildup can be bad for fresh­wa­ter tanks, as well. (It reduces the effi­cien­cy of gaseous exchange, i.e. your water has less oxygen.)

There are numer­ous options for skimmers:

Stand­alone solu­tions work best, but any­thing that agi­tates the water sur­face (and prefer­ably pulls the water itself into the col­umn, à la lily pipe) will do.

Your pri­ma­ry goal is to con­tin­u­al­ly remove any trace of excess organ­ic waste present at the sur­face. If there’s no waste, there’s no bac­te­ria — that means no biofilm.

There are oth­er sig­nif­i­cant ben­e­fits to skim­mers (like increased oxy­gen con­cen­tra­tions and bet­ter CO2 dis­tri­b­u­tion), but skim­mers aren’t for everyone.

If you have a small­er tank, or sim­ply don’t want the extra equip­ment in your tank, a sur­face skim­mer isn’t your only option:

Step 3: Increase Flow

Since that organ­ic waste buildup at the sur­face is what we’re try­ing to pre­vent, increas­ing the flow in your tank also alle­vi­ates the occurence of biofilm.

Your tank’s fil­ter should gen­er­al­ly be at least 10 times the vol­ume of your tank.

That’s enough flow to ensure the entire col­umn of water in your tank is being cir­cu­lat­ed. In near­ly any stan­dard tank, a fil­ter with GPH greater than 10 times your tank size is enough to keep the sur­face agi­tat­ed and allow min­i­mal organ­ic waste buildup.

Your fil­ter intake/​outflow can fur­ther agi­tate the water to con­tin­u­al­ly breakup’ that waste. (As we men­tioned already, lily pipes are a great choice for this.)

Con­ve­nient­ly, high flow in a tank also dras­ti­cal­ly reduces dead spots”, or stag­nant, still areas of water. (This helps — again — with oxy­gen con­cen­tra­tion and CO2 dis­tri­b­u­tion in your tank.)

We’re cre­at­ing a micro­hab­i­tat in our tanks, so it should­n’t be sur­pris­ing that every­thing is interrelated!

Step 4: Check Your Dosing

Most biofilm comes from the buildup of organ­ic waste.

How­ev­er — if you’re using fer­til­iz­er in your tank, there are rare cas­es where that biofilm could actu­al­ly be iron bac­te­ria at the sur­face, feed­ing on the avail­able iron in your water. (This is com­mon­ly seen as a sil­ver-like film” on the water surface.)

Depend­ing on your plant needs, con­sid­er whether you can reduce your dos­ing, or chang­ing the amount of avail­able iron in your fertilizer.

Also con­sid­er swap­ping to a fer­til­iz­er that’s more bio­log­i­cal­ly avail­able, to reduce the amount you actu­al­ly need to put in the tank. (I use Trop­i­ca Spe­cial­ized, but I’ve had suc­cess with NilocG ferts historically.)

In oth­er words, if more” of your fert can be used by plants, you can reduce the amount you’re adding and still get the same growth results.

This is eas­i­er if you dry dose or dose sep­a­rate­ly. For those using a com­plete” fer­til­iz­er, there are few options oth­er than sim­ply reduc­ing the fer­til­iz­er amount overall.

In some cas­es, improp­er­ly man­ag­ing your water para­me­ters can cause organ­ic waste buildup. (i.e. you’re adding too much/​too lit­tle ferts or min­er­als.) More on that here.

Step 5: Recon­sid­er Your Food Amount

Fish food of any kind con­tains pro­teins. (Or at least it should.)

When you add more food than is used” (eat­en), you’re direct­ly con­tribut­ing pro­teins, which is the num­ber 1 con­trib­u­tor to the organ­ic waste in a tank, and can direct­ly cause biofilm itself.

In addi­tion, as your food decays and releas­es oils and oth­er byprod­ucts, that also con­tributes to the biofilm buildup.

Nor­mal­ize your feed­ing times and make it con­sis­tent. This does a few things:

  • Anec­do­tal­ly, it can train” most fish to eat more food at the time it’s provided
  • Gives you more con­text to actu­al­ly see what is (and isn’t) eat­en by your livestock
  • Makes it eas­i­er to see in your water test­ing whether food is con­tribut­ing to ammo­nia buildup
  • Results in gen­er­al­ly-health­i­er fish

You’re prob­a­bly quite a busy per­son — I am, too! I don’t have time to mea­sure and dose food to each of my tanks.

Thank­ful­ly, there are solu­tions for this, and you’ve prob­a­bly seen or used them before: auto-feed­ers.

As cheesy and dat­ed as they appear, they’re a great solu­tion for mak­ing your feed­ings con­sis­tent. (I’m a fan of the reg­u­lar ol’ EHEIM ver­sions — you can see them on Ama­zon here.)

Now It’s Your Turn

And now I’d like to hear from you:

Do you have any ques­tions about biofilm?

Maybe you have an alter­na­tive solu­tion that I did­n’t include here.

Either way, let me know by leav­ing a com­ment below right now.

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