Make Arduino do 2 things at once?

I am very new to arduino and this is my first major project. I am trying to make an aquarium controller with my Arduino Mega. Right now I have the temperature control and the auto top off working. Now I am trying to incorporate a wavemaker by oscillating two pumps constantly while still having the temperature and float switch working so I don’t cook or overflow my tank when the pumps are in their delay. I know the code I have will not do two things at once, but it is as close as I can get. Thanks in advance!

//Wave Maker Variables
int powerhead1 = 2;
int powerhead2 = 3;
float leftdelay;
float rightdelay;

//Temperature Variables
float tempC;
float tempF;
float desiredtemp;
float dataString;
int tempPin = A0;
int sumptempPin = A1;
int heaterled = 4;
int heater = 5;

//Auto Top Off Variables
int fillpump = 6;
int sumpfloatled = 7;
int sumpfloat = A2;

void setup ()
{
Serial.begin(9600);
Serial.println(“Timer Begin”);
pinMode (powerhead1, OUTPUT);
pinMode (powerhead2, OUTPUT);
rightdelay = 1000;
leftdelay = 1000;
desiredtemp = 79;
}

void loop ()
{
leftwave ();
rightwave ();
tempcontrol ();
ATO ();
}

void leftwave ()
{
digitalWrite (powerhead1, HIGH);
Serial.println(“Left On”);
delay(rightdelay);
digitalWrite (powerhead1, LOW);
Serial.println(“Left Off”);
}

void rightwave ()
{
digitalWrite (powerhead2, HIGH);
Serial.println(“Right On”);
delay(leftdelay);
digitalWrite (powerhead2, LOW);
Serial.println(“Right Off”);
}

void tempcontrol ()
{
tempC = analogRead(tempPin);
tempC = (5.0tempC100.0)/1024;
tempF = (tempC*1.8)+32;
dataString= tempF;
String ((byte)tempF);
//heater controlls
if (tempF < desiredtemp)
{
digitalWrite (heaterled, HIGH);
digitalWrite (heater, HIGH);
}
if (tempF > desiredtemp)
{
digitalWrite (heaterled, LOW);
digitalWrite (heater, LOW);
}
delay(500);
}

void ATO ()
{
if (sumpfloat = LOW)
{
digitalWrite (sumpfloatled, LOW);
digitalWrite (fillpump, HIGH);
}
if (sumpfloat = HIGH)
{
digitalWrite (sumpfloatled, HIGH);
digitalWrite (fillpump, LOW);
}
delay(500);
}

First, start here: How to use this forum. Point #7 in particular.

As far as running tasks simultaneously, study, play with, understand and embrace the concepts demonstrated in the BlinkWithoutDelay example.